Moving to England then back to the US

I was wondering if it would be possible to bring my UK wife to the states with me (American) after I've moved to England for a year or 2 on a fiance/spouse visa.

Would I have to move back to the states first and apply for a spouse visa?  Or could I stay in England with her and do the process?

How would I go about starting the whole process?  And would I contact the UK embassy or the US embassy...or both?

You might find this thread helpful:

http://talk.uk-yankee.com/index.php?topic=20181.0

Also the repatriation board:

http://talk.uk-yankee.com/index.php?board=19.0

Good luck!