September? if you are lucky there might be some North Easters starting to appear. They will be very light however.
Your best bet would be Gerroa for the North Easters at that time of the year. Waves are usually small so no worries there.
Other than that you will see Westerlies or Southerlies if you stay in Sydney. In Sydney for the type of sailing you are after I'd recommend Botany Bay. It's mainly bump and jump style sailing. For a spot guide go here:
nswwavesailing.org/spot-guide/Regarding gear rental try Windsurf and Snow (
www.windsurfnsnow.com.au/ ) they should be able to rent you some gear. I'd probably bring a wetsuit and harness as well as harness lines. Best you contact WSS. Sam or Chris will be able to help you out. If you get unstuck try this forum again... there might be other options.