I've not read that much Philosophy to be honest, it depends what you're interested in. I suppose "The Republic" by Plato is a good place to start.

I recommend the book "The Grass Arena" (I've mentioned it on here before I think) that's an enjoyable read, it's the autobiography of John Healy - https://en.wikipedia.org/wiki/The_Grass_Arena (he was born in London to Irish parents).