Does the school have a counsellor (they are quite likely to have a visiting one, if not anyone on staff) and could you or possibly your partner (if relevant) persuade him to see them? If he is depressed the rest of the stuff he needs to do will undoubtedly feel like a mountain to climb. In any case it would likely be better in the long run that he does a year out/works/volunteers/retakes than goes to university in this sort of state, even if he gets the grades to go. At home he has you looking out for him, while at university he will not and dropping out is very expensive these days. Also look at Young Minds for some resources. www.youngminds.org.uk/for_parents
Have you phoned the school to discuss him, attitudes, attainment etc? If not, phone them and get the facts. Then sit down- does he actually want to go to university or is he going through the motions because it is expected? Suggest a year off - apply with actual results- if he wants to go.
My son is just coming up to his A levels this year. He is or has been reasonably confident, active popular boy. He now spends all the time that he is not at college stuck in his room in front of a screen; has offers from universities that he wont go and visit, (needs acceptances in by May 8th), looks terrible, is clearly very worried about is exams and they certainly pile on the pressure at the college hes at. I think his way of dealing with it is to not look at things and ignore them till hey're imminent and then to get into a state about them. He wont talk to me, he wont even go and visit the unis he has offers from; Im afraid he wont get round to it at all, yet he snaps my head off if i ask about it. I dont know where hes up to with his college work; he may well be behind. He is resitting one of his AS's as he didnt do as well as he had thought, but that was because he didnt do any work for it! I have no idea how to deal with all this; leaving him to his own devices(which seemed to be the only way and what he wanted) has seemed to lead to a downward spiral. Not sure how much sense this all makes but Im as confused as i sound.