Gestalt and anyone else who wants to join in:
Rig up on the northern side of North Kirra Surf Lifesaving Club. This is more like a pub than anything else. It's on the beach, just get to North Kirra and drive along the road that runs closest to the beach and you'll see it.
I park in the club carpark, others park just a little bit further north on the road. I think there is a playground there as well. Grass rigging area, shower for afterwards as well.
It's a bit of a walk to the water though (feels like 100m!).
The sandbank pretty much starts just to the south of the club, and extends a fair distance. I've never seen flat water on the inside but it's rumoured to exist. Getting out can be challenging if you're not very experienced. If the wind's right you can blast along the beach for a good kilometre, but be careful not to go too far downwind (close to the beach) as the beach curves and you end up running out of water trying to get back to where you started from.
Also a word from the wise: Have a good hard look at the layout of buildings around the spot where you started, as it's easy to get off at the wrong stop and then not be able to get out again due to the crashing shorebreak and lack of sandbank, making you do the walk of shame for no reason. Even more embarassing is realising that you've just walked 200m the wrong way.