I live in England too so would've known the similar school process. I'm 19 and finished year 13 last year.

I always laughed at the few kids who were sitting in lessons after taking drugs round the back of some part of the school or on the field, then would come back to the lessons. Sometimes they'd go white, everyone would secretly laugh at them (although the usual type to be smoking at this age would be in some sort of clique where doing things this young is cool), sometimes they'd get away with it and it'd be funny.

Just put the weed away for 4 years, find a playstation or a football, and play. That's more fun.