Mate of mine did it a few weeks back, he really enjoyed it and said it upped his game such a lot - he did whinge about the lunch tho, but that's cos he's a greedy beggar!
Certainly intending to do it once the DAS is out of the way.
South or North? I did the South one at Bromley last year - was excellent and may book again this year. You don't get a cheaper days advanced riding than £30.