I did it a few years ago, when I first got the Blade. For me it was brilliant as it was my first litre bike and I had only done 1 TD prior to that, so wanted to learn much better bike control and get an idea of what I can do with it on track. The difference in my riding skill before and after was night and day. Learning how to tip in late, quickly and drive off the apex (along with the theory behind it) was very valuable, but if you're Inters-level of proficiency on a track then you would be better off with 1:1 tuition rather than Level 1 CSS or Ron Haslam.
PS. Tempting though it is I wouldn't hire one of their 899 Minigales to do it. Much better doing it on your own bike, not to mention cheaper!