As a brit who grew up in the UK and moved to the US in my late 20s, and subsequently spent nearly 20 years living in the US on both coasts here's my input:
1) Try before you buy: living in a country is very very different to vacationing there. The advice to get a student year in the UK is a good one if it's possible. The UK is a lovely country but it's a very different place to California - in many ways better (healthcare, less materialistic), in some ways worse (Brits tend to be very negative/can't do folk).
2) The US is a big and very diverse place. The best thing I ever did in my time in the US was to move from San Jose CA to Boston MA. For 3 months of each year the weather in MA is "challenging", but in every other way I am much much happier here than in CA. New England really is a halfway point culturally to "old" England in the respect that it is less materialistic, more family focused and has more consistent education and social services (I won't say better because California has some excellent schools, but also a lot of terrible schools). Massachusetts has the nations lowest divorce rate, lowest rate of uninsured drivers, is consistently top of national school rankings.
So if you can't get to old England try New England for a while - Boston is a great, great city, large enough to have a lot going on, but small enough to not be intimidating, and with very few really bad crime areas. And you don't need a visa.
Best of luck with your future moves.