UK vs. USA
Scientifics,
Simple as this mate, if you are learning to drive you can go for lessons over a number of weeks or an intense course.
In the US you can fly virtually every day because of the weather, from what I'm lead to believe the FAA qualifications look more for practical pilot skill where as the JAA look to see that you know the theory before flying in an aircraft.
Yes the airspace rules are different to a degree as is the communication with ATC and charts. But I defy anyone on here to say that someone with the nonse to attain a PPL can't master the UK equivalent information upon their return. As for open airspace in the UK versus congested airspace here, I'd say pick a flying school based in a high density area, problem solved.
Also if you overrun in the UK, you go home and then return to the school as and when you can. In the US you have a flight booked and work to get back for, so there is a greater degree of urgency to get everything finished.
In the UK you may have distractions and as sure as the sun will rise in the East tomorrow, you'll be grounded on a few occasions because of our inclement weather.
All I can to you is, if you opt for the US ensure you pick a school with a good track record and when you phone up offering your business (rember £3/4 grand for a PPL to £30/40 grand for a fAPTL gives you the right to question them rigourously), ask pertinent questions such as, where are the intructors from, what qualifications do they have and from which authority?
Stephen