Hi, Me and my 11 year old son have just completed what you want to do. We found that the best option was to do the PADI REFFERAL. Aberdeen and the North sea is freezing and was advised not to dive due to the cold.
WE purchased the padi Ultimate Crew Pack. This contains all the books and info you will need to complete part 1 of the refferal in the UK.
We done all our confined water elements in the pool with extra sessions if required.
The dive centre will complete all the paperwork required for you to take to Florida to complete part 2 of your qualification. You will have to sit the theory side of the referral in the uk as after the confined water there is a diving test which you require to present to the dive centre in Florida.
The best advise i can give to you is get your son to read the OW manual several times over so he understands basic diving knowledge. Answer all the questions as our instructor was very thouough with us. We completed part 2 in Spain which was great. Paperwork was all completed correctly, diving was fab and we became OW qualified.
We are going to Florida this year and have booked the Epcot dive experience, are there any local diving places you could reccommend as we are staying at Tuscan Hills area.
Good luck he will love it...
MARK.