Jett not being in school is REALLY concerning! I cannot think of any justification for this at all. The only possibility is that he's been registered for Home Schooling but we all know that Katie is not cut out for that - not only is she rarely home (out at nail bars and night clubs much of the time) but she also doesn't have the personality, commitment or, I'm afraid to say, the intelligence or education herself to be able to do it. She MIGHT be buying tutors in perhaps but, knowing what I do of her, I'm not sure I can see that happening.
But education aside (and yes, I think it seems more than possible the lad has some SEN going on), there is a very real safeguarding issue here, with Carl allegedly on the scene, drug-taking, excess alcohol and decidedly dodgy (in my opinion) photo-shoots happening in the house for OF. Also, there appear to be very few, if any, rules or routines in the household.
I don't think we know the half of what's going on. Kieran must be worried sick.