I can recommend bike train Wales based in Cwmbran and abergavenny as well now I think. Did my training (das) with them just over two years ago and found them really good.
I'll second that. Nick, Jullian, Darren and Carl took me from CBT to DAS pass in three weeks. I had no experiance of riding other than a blast on an old scrambler *cough* years ago. Can't reccomend them enough.

Matt