Ok guys, first of all many thanks to anyone who answered. I took my time to answer cause I wanted to get more experiences either first person or from my friends to have a better idea of the situation cause your answers confused me a bit.

However i would like to reply to everyone:

I am used to live my relationships with girls like this but since I am in England the impressions I have is that it is not like that at all. For example a girl that on the first date asked me if i was Jewish just in case we married. If you're asking me this question it means you have marriage in mind, that's why you are dating me, that's your aim, that scares me so much that I normally run away.
No italian girl would have ever made such question and if she was attracted she would have dated me being not the time to think about marriage yet.
What I mean is that I feel the general approach is completely different: you can date cause you're attracted and only after a while you consider if the situation can evolve into something else or you can date to find a person to settle down long term.
In the second case your approach will be really different, you will consider if that person has a job, owns a car and stuff like that.
You say it's nothing serious until otherwise said but from my experience I can say since I am here I meet only girls who have the second approach and this makes me too much unconfortable.
Before coming here normality was to have a relaxed approach, we hang out together and have sex just because we are attracted to each other. Things may or may not evolve into something more serious.
Since i arrived here girls seem to have the second type of approach, they check soon if you can be a good long term partner and if not they dump you. And this is really the whole problem and what makes me feel very unconfortable and run away very soon. i got to the point to which I am afraidn to say something wrong.

Ok, it has never happened to me to hear an english girl saying that, actually talking about it with some of them i heard them replying about self respect and than that would mean being used. While my italian friends (females) speak really freely about it, about having sex just for sex's sake with someone and they normally do.
If we talk about apps like tinder then there are girls who say they are not looking for anything serious or that thay don't know yet, so I don't see why it is bad saying that on an app. Some of them do, so it is not bad but those girls are rare and I am sure they will have plenty of matches.

That's exactly what i said to the last girl met via tinder and she replied "yes I too want to find someone to settle down with". i was a bit puzzled not knowing if she understood and I changed topic.

I think you completely missed the charachter. i was raised as a catholic but soon when i was adolescent I abandoned my faith for the atheist path and I have always surrounded myself with super liberal and progressist thinking people.

in facts:

As I said previously I know all my female italian friends like to have sex, we talk about it freely. I don't have any criticizing or judging thought about them when thay tell me about it. I talk with them like I talk with men and they say they enjoy sex as men do so why shall i think what you say?
When I said I don't want to take advantage of anyone I meant that if you're looking for a husband and I am not into anything serious I am wasting your time and taking advantage of you. That's why i think it is correct to be clear soon and it is what i have always done.

i didn't understand this bit.

As I said i don't believe in god and i already live by my morals.

he is great indeed and he made me understand that everything is possible. I was hanging out with him for an year and I was thinking he was a bit creepy. he is funny, girls laugh, but sometimes i was thinking he was creepy. For an entire year he didn't pick up anything, then one day something clicked he had his first telephone number and after that night he started to pick up one or 2 girls every night.
So I understood that maybe it is something inside you, something you communicate to them and he, insisting into trying, developed this skill.
One night we were together and he apporached 2 girls sat on a table. It was a bit embarassing but with a couple of jokes we softened the situation. then we left. After a while one the girls came to me, we talked, escalated, kissed then she went home but left me her telephone number. After that night i understood that i have to work on overcoming what i consider embarassing or creepy. i have always thought 2 girls sitting on a table don't want to be annoyed. If you are standing and you approach them at their table it looks really creepy to me but it worked so i understood that not only was a good thing to do but it earned me a girl to date. After that night I tried to overcome those kind of limits and i can say that for 3 months i picked up a girl every night as well/ But then I had a break in night outs and when i composed this post I was back into the nightlife since shortly and wasn't having any succcess. So i think it is about practice and really everyone can do it. Just kill your shyness and do it. you will get 1000 "I am not interested" but you keep doing it.

Now, probably I have been unlucky but seriously since I am here I am struggling a lot to find a sexual partner. i managed to find girls to date, but if they were met at a club they didn't want to have sex soon and i didn't manage to go past the 3rd date with any of them. if they are met on tinder either i realize i don't like them at all, or they show too much seriousness and i run away or they don't like me.
The only succesful interaction I had was with a feminist belgian girl into polyamory met on feeld (it is tinder for sex) and a greek girl met on a club.
Regarding this greek girl I can say she behaved in a very Italian way: We met because my friend approached her firend in a club. We spoke a bit then we left.
Then i met her again another day in another club, she waved at me and called my name. I wasn't remembering her but i pretended I did. then she spend the next hour with me, forgetting about her friends, she even bought me a drink. Soon after i kissed her. While we were kissing she said she lived close to the club. i asked her to show me her place. She said she would have loved to go for a coffee first. I started talking about something else. When the club closed she said she was going home and i said I needed to wait half an hour for my bus but i could have walked with her for a bit. i walked till her house and she asked me to come in and we went straight into bed.
With no english girl i had this success. I even managed to watch a film with the first girl I picked up, the one who was sitting a the table and my friend approached them, at her place but she refused to have sex, saying we would have done it next time. but there wasn't any next time cause we had an argument that ended into not texting each other anymore.

So, this is a problem that is affecting my mental health. In england I found a good job in the NHS which is really valuable and I would'nt like to leave it but the lack of pussy is killing me and i am seriously considering to go back to italy.
Probably it is just a matter of different ways, different codes of seduction.
I am really interested into knowing how you guys get laid, without feeling obliged to commit, if you do. I would love to hear about your experiences just to prove I am wrong and that probably I have been unlucky so far. I accept any suggestion!!!

So my question is: do i really need to tell them that I am looking to sette down and date them a few times to have some sex? Or am i just being naive and the limit is only in my mind (for this reason i would appreciate to hear your experiences).
I have also to add that in Italy i have never used tinder but everything happens going around, meeting people, just a few girls have children before 30 years old (that's a continental thing, not just italian) while here the average 30 year old has at least 2 so they are more oriented towards finding a father for their children. Also every English girl i know has a boyfriend from long time, the single girl who enjoys her life and decides to date someone more seriously only when she finds someone worth (and that doesn't mean they want necessarily to make babies with them) it is something i have never seen here, whereas is common where i come from.
Other thing i will never understand: girls I've been on a first date with here, text their mums after, to let them know the date went well. The fact that their mums know doesn't put way too much pressure on them on how to behave? I am used to people who tells parents and friends about someone they are dating only when that someone become the official boyfriend/girlfriend. Until that moment they say they meet a friend and what they do is their business.

So I really want to know what am I doing wrong, if i have been unlucky or naive or if that is just the way things work here.

Thank you very much in davance.