i did a simliar thing, after completing a university air squadron course, and RAF fly schorlarship in UK I finished up the PPL in states.
I think you should go and complete the whole course in US, when you come back with a shiny PPL you will need to be checked out by the club you fly from anyway and so will still need some hours upon return, get the whole PPL for cheap in states, with good continuity then upon return to UK you will hopefully have spare mental capacity to cope with different airspace/radio etc as you know how to handle the a/c by having a PPL.