I have a 12yr old son too and after school he goes to the local library. Luckily it open every evening until 5pm so I collect him from there. He gets to do his homework and the librarians have got to know him do I benefit from free childcare. In the past few weeks he has started to come home and been on his own for a couple of hours. Now the clocks have gone back and it’s darker, he wants to revert back to the library. That works for me. Check out if there’s a library local to school and check opening hours.