But I wonder how useful it would be in the UK with our weather?
There is an enduring myth that the UK has bad weather. The USA has thunderstorms which will dismantle a 747, temperatures far more extreme than the UK, has the same warm/cold fronts, has mountains, deserts, the lot.
The thing is, one can't pick just one single thing and try to change that on the basis that it works well elsewhere. The UK airspace system "works" because we have loads of Class G at low level. We have airports with instrument approaches where (subject to PPR) you can just turn up and ask for an ILS or whatever. We can fly in cloud in Class G non-radio. We have the IMC Rating which legalises all these practices.
We also have an IR which is set up for would-be airline pilots (mostly un/under-employed young men with plenty of time to sit exams) which is out of practical reach of most pilots who are at the stage of their life where they can afford to fly IFR in their own plane, but that doesn't matter because one can fly around in cloud in Class G...
We also have an ATS service with a water-tight separation between IFR enroute sectors, and all the "dross" below that, with the latter getting no service, unless they can get some "limited radar due to controller workload" scraps from some LARS unit.
The US model would work perfectly in Europe, but only if the other bits they have were all in place: Class A base at 18000ft, a proper ATS service for everybody, an practical "private IR", etc.
Some of the US stuff, like a decent ATS service, isn't going to happen in the UK unless the funding system is overhauled (ATC is nationalised, basically) which isn't going to happen. But the rest they could do. France manages OK for example.