TripleT said:
The red letter days won't improve your driver skills. I've done one, they're fun, but they teach you how to avoid getting into trouble and smashing they're nice cars (thats all they care about!), not how to control etc.
As fox said, work your way up
My father's an instructor at the schools that Brands Hatch run, I believe Red Letter Days cover the whole group of tracks Brands is a part of.
On the subject of punters/improvement, he says anyone willing to learn and open to criticism/teaching will learn a lot. Anyone who thinks they're the nuts and think they know it all already won't learn a thing.
Of course I don't know where you went, and some of the instructors may be better than others, but all the tracks in the group (includes Silverstone and a few more) run their days the same way, with the same pool of instructors.
Also, the reason the instructor doesn't want you to damage the car isn't because he cares about the car, it's because he cares about his job
If you flip it or badly smash it up while under instruction, your instructor gets the sack or at very least severely gets it in the neck.
If you're up for learning, will take criticism and tuition well, and listen to what they say, you will learn.
Don't buy it from Red Letter days though, buy it direct from whatever circuit/group you want to go to, it's much cheaper.