Just back from Wales where I spent the weekend at Plas y Brenin doing the Alpine Prep course. Just wanted to recommend it to everyone, especially if you're eligible for the subsidised rate (via John Conville).
I never expected it to be run by such an accomplished pair of climbers, it's very professional and they'll take you from walking around roped up in a field to moving together alpine style on a III - Diff ridge.
Also they have cake, lots of cake.