If you pay for a sailing school, you'll learn how to sail on a small boat. This will make you a better, big boat sailor. Hopefully it'll also help you decide if you want a small boat, or if you really want to step up to that 30 footer.
Agree. Get spanked around in a small boat for a while. Might be cheaper to just buy a small boat after taking a few lessons. Can usually sell a boat for about what you buy it for. Then take lessons on bigger boats b/f buying. OTOH, many have jumped right into multi-ton boats w/o any experience.