Just go to Sanctuary Point, No camping on the water but it's only a short drive and you can leave your gear there rigged all day without a problem. It's only a short walk to the shops for lunch and there is a playground for the kiddies. Take a bat & ball, Frisbee and the like and you'll have a great day. There is also heaps of sailors there that can give you some tips, It's by far the best learners spot on the east coast.
At Gerroa at the moment the river is closed which is holdling some water down by the riverside caravan park, it's shallow enough in most parts to be only waist deep or less. The nor'easters wouldn't get in there but anything south to west would be ok.
I stayed at a house up at wallis/smiths lake a few years back, I think it was coomba park or something like that. I wasn't into windsurfing then but we could just walk across the street and had direct acces to the lake from a park, It was near a boat club.
Places like you want would be more easily found on a fresh water lake like Burrinjuck dam, Glenbawn dam, Keepit or any of the others through the riverina or hunter area. Most of these have camping grounds lake side and as a bonus no sharks.....But some of the cod are big enough to swallow you whole.
......Just go to SP, But i would advise to saty in Husky and drive the 10 mins to SP...Much better accomidation to be found at Husky.....And it's close to the pub