tricky dicky...in reply to your query...i have FAA instructor ratings..and i have instructed in the states for the last year building about 500 hrs in 12 months and i wasnt going at it full on...its not that expensive...you should get in touch with a school...who will then be able to evaluate what you will be required to do to as far as getting a CPL(faa) and the your CFI...its not a bad idea as if you dont get your UK ATP sorted its quite possible to left out in the cold by new JAR regs...so get the flight time you need and get the UK ATP asap...if you need more info get in touch on my e-mail..best of luck