Usually an unrestricted passport is required so a US passport should be fine (provided additional travel authority not required outside of the U.K - check
http://www.uscis.gov/portal/site/uscis ).
Donna, out of curiosity, why would you want to leave a job in the U.S. to move to a place where there aren't many jobs? Can't you convince the 'other half' to move stateside? Surely the quality of life has to be better?