I've lived in the U.S. for 12 years and am a dual citizen. If the right position opened up in the U.K., I would consider going back, but I am quite happy here. I probably prefer visiting "home" rather than living there. I work in higher education and the system here is far more meritocratic.
Neil Tennant had a house in Rye. I waited on him and Janet Street-Porter. She ordered a creme caramel, which was highly amusing given her horrid voice.
I grew up in England and left when I was 21. I have spent the last eleven years abroad, so I will answer this by what I miss and don't miss:
I miss the tradition/history/sense of place.
I do not miss the cramped space in which people tend to live.
I think Postgraduate degrees are a different kettle of fish. I am not sure that the Student Loans Company offer loans for postgraduate education. I don't remember them doing so in 2001, but that was over a decade ago.
I used to live in Reno, which by American standards is close to the Bay Area.
San Francisco is very cosmopolitan. And bloody expensive.
I would ask your company to help with relocation. A simple e-mail to some of the local employees with likely answer many of your questions.
My son is the first in my male line not to be born in Sussex since the eighteenth-century. Or, as I like to put it, since before the United States was a country.
I bucked the trend to be born in Hastings, instead of Rye.
My wife and I managed it. And were went to University on opposite sides of the Atlantic in an era before webcams.
It just meant that I spend all my loan money on prostitutes...