See this from the government's view.

On one argument they want folks out spending money so that the economy progresses (or recovers, more like)

On the other hand, they don't want the NHS to be overwhelmed, and thus have loads of people ultimately not contributing to the economy and instead being ill or worse, dying. Both of those happening is expensive generally.

Having said that hospital rates are pretty low atm despite the rise in UK cases so I get the feeling they're experimenting.