Couldn't have put it better myself flyre8. I honestly think that going to the US to do a PPL as quickly as possible is a false economy - particularly if you're planning to go commercial.
Airspace and RT are vastly different between the UK and US, and as others have said, the PPL lays the foundations for all your future flying. OK, the exchange rate is great - you may well save a grand or two in Florida, but when you get into CPL & IR training, mistakes costs thousands - literally. Three hours extra training in a Duchess (not unusual) is a thousand pounds, a partial in a skills test is a thousand pounds . . .
The learning curve is very steep in commercial training and you want as many things in your favour as possible. Being familiar with the airspace is a big deal - I have seen people struggle unnecessarily because they weren't used to MATZ crossings, flying in class D airspace, tracking NDBs etc.
I think the old adage is true - it's better to train in the same country you want to work in.