All I'm saying is do the research. I was at HAI a few years ago and I was astonished by the number of people doing FAA CPL licences who didn't even know you couldn't use them in the UK. There was even quite a few people who had signed up for entire PPL/CPL/IR courses who had never even been in a helicopter before (not ever a trial lesson). Amazing.
I would say 20-30% of people seemed to give it very little research and you could tell they were the ones who were not going to ever make a living as a pilot. ie - Do the FAA licences, come back to the UK $50,000 lighter, and go back to their old job.
Yes, there are ways to stay in the USA and work, but apart from marrying, not many at all.
Converting a PPL may be easier in some countries, but a CPL/IR/FI is another matter entirely. Ask anyone who has "converted" a FAA IR to a JAA one.