I'm nowhere near Cardiff, tempo, so can't help you there. However, I do have some experience which may help. I joined a group for six weekly sessions to stop smoking. It helped because no way was I going to be labelled a failure in front of the rest of the group. On my own I would have scored yet another failure. We each paired off with a "buddy" and phoned each other regularly. I made it through those critical first weeks.
Secondly, I'm an alcoholic; a recovering one only because of Alcoholics Anonymous. That worked by making me feel I was not alone any more, nor without hope.
Some people seem to have a need to do everything in groups. For myself, I'm the type who normally prefers to sort my problems out by myself. I needed the strength of the group for those two problems though.
I hope that's helpful.