Your best bet is to get an FAA PPL and hour build in the states - its way cheaper than the UK.
People keep talking about 'converting' licenses - totally unneccesary with a PPL. You can fly in the UK on G or N reg with an FAA PPL. Once you've got it, you'll need to do a flight review with a CFI every 24 months to keep using it - way easier I believe, than a JAR license - plus it's not type specific - if you take your PPL checkride in an R22 you can fly anything under 12,500lbs.
As i understand it, under JAR you have to take a seperate test in each type you want to fly (anybody?)
Of course, when you come back and rent you'll need to show an FI that you can navigate using those rediculously complicated CAA charts, but other than that you should be good to go.
Persononally, I'd also get FAA commercial - when you come back you can convert it, which means you don't have to do the full groundschool (i think 400 hrs ish at cpl level) and you wont have to do the 30hrs flying either - just take all the tests.
Or just move to the US permanently and skip all the bulls**t