As Jay said mate, better to pay for tuition at individual circuits, sometimes it's even free! Good instructors will teach the lines specifically for the track and your car.May also go into mechanical sympathy and smoothness depending on how much time you book.
Plus what they teach you will probably gain you seconds off a lap time so considered by most to be the best performance gain you can get and one of the cheapest when you look at it like that, what costs you say £25 off them would probably cost up to a grand in parts to reap the same benefit.