Welcome back to windsurfing! You are lucky to live in Florida where it is warm enough (most of the time...) to windsurf much of the year.
For the area where you live, there is some help available. My recommendation would be to look into these places. North Beach is farther north than you mention, but it may be your best shot. Britt Viehman, the owner/instructor, is doing a good job in that area. Island Style is in Sarasota, but seems to lean more towards kiting, but the last time I was in the area, they did have a good instructor. Then there is Ace Performer on the road from Fort Myers to Sanibel, but I don't have a good idea about their instruction in recent years.
Contact Britt at North Beach Windsurfing...he'll set you up right.
North Beach Windsurfing
Island Style Wind & Watersport
2433 N Tamiami Trl
Sarasota, FL 34234
Hope this helps and let us know how it goes!