As steps you can take, I suggest like another contributor, that you contact MIND, and google other mental health support groups - there are lots many of which involve group meetings and these have the benefit that depressed young people can feel some kind of normalisation about their situation rather than feeling isolated. He should also self-refer for counselling but someone may need to do this because usually at the initial stage there will be a triage counsellor who will need to take details of how he feels over the phone and he may not be up to that. But he should, with your help maybe, be proactive in seeking help. He might also think about a little volunteering whilst he is unemployed. That might also get him out of the house.
The bigger problem is however the political nature of decisions about providing for mental health issues. Living in London I am in the thick of an enormous population, knife and gun crime, and the blatant evidence that we need more funding for mental health care but in the age of austerity there's not a chance of this - it's all rhetoric - and what beats me is that so many of those needing help still vote Tory!!