I suspect if you are in Houston for 18 months, you might want to get an FAA Certificate (PPL) at whichever school nearby feels right for you, rather than try and find a JAA one. That'll mean doing the US ground studies.
You can fly on your FAA cert when you get back to the UK, but I'd get some dual-navex time when you do. You can later convert to a JAA PPL if you want, but you might not want to initially.
Make sure you know and comply with TSA regs on training 'aliens'. (lots of info on PPRUNE)