When I had a Caterham I went on a half day course with Cadence
http://www.cadence.co.uk/ and it was the best £300 I think I've ever spent (excluding that stag weekend in Estonia but that's another story....).
It was a "road craft" - built around improving awareness, lines, positioning, setup and so on. It was essentially to make you a safer driver on the road, though off course, the underlying tone is to get the most out of a high performance car, so there was plenty of guidance around heel 'n toe, getting onto the power appropriately, overtaking safely and so on.
At the end of the day, I felt that I was actually progressing
slower than before, however, that off course is the illusion that you create if you are driving more smoothly and with better awareness.
Most reputable driving schools will give you this result - there are loads advertised in the back of PP.
I assure you it'll be money well spent!