I went on a skidpan course through the IAM which was held at the GM Bus depot in Ancoats, Manchester. Instead of going out in a modified car we took our own cars out on the wet, oily yard. At the time I was driving a very tail-happy Vauxhall Chevette and to kill time once all the theory and education was out of the way we had carte blanche to do whatever we wanted. There was me and a guy in a Sierra (the only two who brought rear wheel drive cars) having our own competition to see who could do the most spectacular powerslides. All in complete safety too!
That day was great fun, and the experience I gained has kept me out of ditches many times since. Wherever you find the courses, I can't recommend them highly enough.