If he's on medication for depression, he should be eligible for ( if not already receiving) psychiatric help, and within the psychiatric department there are people trained to help in this kind of situation.
I would suggest the Jobcentre is not really the way to go, he sounds as if he has little self-confidence, and would need someone to give him moral support in a jobcentre.
Good luck, it aint easy, but there is help out there. You could try the claimants union (I don't know if they still exist) or citizens advice bureau, these may be online (jobcentre may be online).