There used to be something called the Civil Defence Corp - basically each area (county?) would practice and plan for what they would do in the event of bombing/attack - how they would get information to the public, public safety, infrastructure, coordinating with central govt and emergency services etc. There were still community public air raid shelter and bunkers, sirens, from WW2 and these formed part of their planning. They came under the jurisdiction of he Home Office and had funding and everything.
Then atm free the Cold War the funding was cut, plans got quietly shelved and the whole thing was disbanded. Shelters and bunkers were forgotten, sold, left to decay, repurposed.
So now, even if your local council is hastily trying to plan for ‘what if’ - there’s nothing really for them to offer - there’s nowhere they can tell you to go, there’s possibly shelters under council offices, but that’s no good for the rest of us. I don’t even know that there’s any mass notification system that would reliably get any warnings out.
So basically - don’t rely on the hope or expectation that anyone ‘higher up’ has planned for the safety and survival of the public at large. They haven’t, and in reality they can’t now. It would be too late anyway. They can’t possibly build enough public nuclear bunkers all over the UK and have them stocked and ready for the entire population.
So, if you really feel the need - it’s up to you to plan whatever you feel is best for yourself and your family.
en.m.wikipedia.org/wiki/Civil_Defence_Corps
This old Panorama episode (titled ‘if the bomb drops) from the 1980s shows what was left of the CDC doing their little planning exercises, and talks about how all the shelters have been left to decay etc. Quite an interesting, if depressing watch.