Fellow Brit who moved out here 4 years ago.. I say go for it, especially if Google are going to sponsor your H1B. Make sure you completely understand the visa process and timeline though (if it's H1B you may have to wait a period of time before you can actually move). Don't forget you could always move jobs in a year so Google is a great 'landing' into the Bay Area.

If you have 11 years experience $110k seems a little low but it might be more than you are getting in UK (I was always paid shit in UK) and cost of living is lower here in the Bay Area (even in SF compared to London). Google is known for paying a little lower than average AND they will expect you to really put in the hours. I don't know many Googlers who actually get to work on their 20% time projects, either.

I personally would move to the City (San Francisco) and commute down in the Google busses.

At this point there are not going to be many firms that will pay the ~$20k for the visa application so I say go for it and then reassess what you REALLY want to do while you are out here.

Best of luck!