Got to agree with Johnnypick's advice. Do your FAA IR and not only will you have a head start on the ATPL theory (you'll know the Jepp plates and charts inside out, and have a pretty good handle on gyroscopes and practical met) but you'll be able to convert to the JAR IR with 10 hours Frasca sim and 5 hours in a twin (minimum). So, say, 4,000 bucks for the FAA IR plus, say another 2,000 bucks to convert to the JAR IR means quite a significant saving--about 6,000 pounds, I reckon.
At which point you could put those savings towards some more hour building in the US; so why not do the initial FAA single engine CPL--it's laughably easy--and you can then convert this to the JAR equivalent and realise even more savings as you'd only have to do the JAA CPL skills test as a minimum.
Or, if you're just wanting some cross country hours I'd thoroughly recommend the west coast. I did some flying in Florida and found it flat and mind-numbingly boring. I've done some solo trips out of San Diego that I'll never ever forget; hard IFR solo LAX, 2,500 mile round trip to the San Juan Islands and Canada over the Oregon wilderness and a diversion flying inside a collapsed volcano on the way back (try doing that in the UK...). I've had the pleasure of flying through some wonderful terrain; Mount Rainer, Mt St Helens (still smoking), Mount Adams, all within some shockingly picturesque scenery, I've seen sunsets over the pacific above a thick marine layer which are just unbelievably pretty and, getting bored of the mountains, valleys and forests, there always the desert east: Arizona, Utah, New Mexico. San Francisco, Las Vegas, Grand Canyon, Phoenix, Yosemite Valley, Death Valley, Palm Springs, Catalina Island are all a stone's throw away.
I've certainly had the time of my life.
In fact, if you do the maths, you'll find that for what it costs to get a fATPL with 250 hours flying in UK, you can get a fATPL with 1,000 hours and foreign ICAO professional licences and instructor ratings with considerably more experience for the same price if you take advantage of the new conversion regs. The question is, however, which route would impress a prospective employer the most? Well, who knows.