Hi Peter, firstly I don't have experience of befriending within mental health or autism field.

However I do have a couple of friends who are volunteer befrienders with older peoples charities. What they do is go out into the community with the people they befriend and keep them company and help them with tasks they may find difficult - this helps those people maintain their independence. Both my friends enjoy their befriending roles, they aren't paid but do get expenses (for example travel costs) reimbursed, the people they befriend seem happy with the arrangement too. They are limited in the support they can provide though, it is a few hours a week and usually an activity and a chat kind of thing.