If you're looking for a one day experience I can't help you. I can, however, highly recommend the
Under 17 Car Club. I'm sure you can go for a day and both see how it operates, and potentially participate (but you'd have to check with them). They're highly professional and have been doing it for donkey's years. They're a charity, not there to make money out of you, but run for their members' benefit. The drivers they turn out are very competent and mature, far more so than the normal product of a few sessions with an ADI. That said, some on-road experience coming up to the test is usually needed as well.
HTH.