What you're saying is that you would like the UK to not have to be a major part of a Western led military alliance that aims to ensures peace, nuclear non-proliferation, and maintains the status quo. Unfortunately we have to do that because no one else will. Isolationism doesn't work, if you sit back you end up with Russia deciding that a few of those Baltic states rightfully belong to them and there's no one who's going to step in, you have China deciding that they own more and more territory around South East Asia and then suddenly they want some Japanese Islands because of what happened in WW2, then suddenly Japan is developing nuclear weapons to defend themselves, plus the entire rest of the world does whatever the **** they want, why wouldn't Iran invade Israel with the backing of some Arab states? Why wouldn't Israel nuke Iran if they think they pose a credible threat to their existence?
Isolationism doesn't work, it didn't work in the 1930's when America tried it and it won't work now.