When Otis leaves O's clinic exasperated, he leaves his bag on the floor and leaves with Eric, however in the next scene the bag appears on his back again.
It's stated that Adam has chosen not to continue with education - although historically compulsory education ended at 16 years old in the UK, it was extended to 18 several years ago.
Adam would therefore need to be in sixth form school or in an apprenticeship- he does ultimately start an apprenticeship, but this would have needed to be organized before September, when school term starts.