Scoobster
You seem very entusiastic and are taking a sensible approach. You might as well get your PPL training started in the US and maybe do some hour building at the same time. Should the CAA then come up trumps you can start the ATP exams straight away and use the hours towards JAA ratings. Also remember that the EASA are taking over and it is expected that they will control flight crew licencing by 2009, so this might also be an opportunity for you.
There are a lot of others that can give you more accurate info on the Biz jet sceene, but it seems like a LOT of Biz aircraft in the UK are on the N register. I feel that they will also be looking at a LOT of hours.
If you go to Canada, there is some fantastic flying to be done outside the airlines, so look at the whole picture.
At the begining we all like to have a plan, just a straight line to follow (not supprising considering the costs) but life is not like that and tends to shine on the active and "go getter". In short it will be harder with only an FAA licence, but you will be able to get a rewarding career if you put enough in.