Depends on yr age. If under 40, learn to sail
racing dinghies; you'll learn more there than you'll ever pick up on a big
boat and that knowledge will make big
boat sailing a doddle (well, almost). Largs Bay SC (or Brighton & Seacliff SC if you're down that end of the coast) have good
training programs.
If you're past that age, go to the Squadron; they have good adult training on
keel boats.