SoCal - Thanks for the quick reply. Yes, my trip is to Orlando, so was thinking of one of the JAR recognised flight schools there.
I've not yet got my PPL license - up to 45 hours now but not sat the GST. It's extremely unlikely I would have the license/paperwork completed before my trip. I understand that you can do the night rating either before or after gaining the PPL, so thought this would fit either way.
Main reasons for considering this option are:
a) My home airfield doesn't have lighting, so will have to do this elsewhere anyway
b) Weather in November likely to cause fewer cancellations
c) Any flying in another country would broaden my experience
Will check this up with the USCIS and the flight school to ensure I have this in writing.