I've done racing school but it was racing yachts, not cars.
I also teach car control and performance driving at all levels. If you are looking for a way to improve your skill, my suggestion is to find a course that will take you to the next level in your driving. A novice will benefit most from a car control clinic or performance driving school. A more advanced driver will benefit from advanced performance driving courses by PCA, Bondurant, or Barber. An advanced driver looking to enter licensed club racing will benefit from a racing school where they teach starting techniques, working traffic to your advantage, avoiding contact, passing tactics, and defensive moves.
Choosing a racing school without advanced driving skills will be fun but you won't get as much out of the course as someone with more performance driving experience.