There isn't any amount needed, its a open track day practice for anyone! More than likely you'll be out there with proper race cars, Although in saying that, last time i went out with a mate they hada 2 sessions, 1 for cams licence holders and the other for non licence holders! just so people don't hold up the real race car people! speaking of which i will be out there hopefully in 2 weeks when we run our IP car, provided we get the engine in!