I certainly didn't get to play D&D at school - I'm not entirely sure anyone at any school I went to had any familiarity with it.

(I did get pulled out of our elementary school equivalent once a week on a special programme, but it was anger management not gifted and talented. I can't testify to grand effectiveness since I don't recall much from back then in detail but there were a couple of _spectacular_ instances in my mid and late teens that suggest that something along those lines would have been a good idea)

My first bid at actual roleplaying was at university but before that I did come across the concept via encountering at roughly the same time Joel Rosenberg's Guardians of the Flame (well, the first book, which I found in a discount store and bought mostly for the dragon on the cover) and a set of three Tunnels and Trolls adventure books that the school librarian more or less unloaded on me in the assumption no one else was ever likely to want to borrow them. (I generally got on well with school librarians).

I picked up a AD&D game book second hand at some point in my teens but I'm pretty sure I didn't actually play any D&D until 3.5 when I was twenty or so. The first RPG I actually played was SLA Industries, a grim-dark science fiction game which was fairly entertaining either because or despite it's more or less a really bad Saturday night in Glasgow with science fiction tropes bolted on.