Sounds like you got off to a good start with some windsurfing lessons at Poole Harbour.
Its a great place to learn & progress with your windsurfing skills. The effective season is really between May & Oct, outside of these times the water just gets too cold to enjoy the learning process!
If you are ever back down Poole way check out:
for windsurfing lessons, equipment hire or just some friendly advice.
Poole Windsurfing also have a great windsurfing information site Top Windsurfing Tips & News
which provides news, reviews, advice & discussions. Tips on techniques, bargain buys, travel destinations & equipment reviews. Regular how-to articles, video posts & latest windsurfing news - weekly summary.