Hi Harrow,
Sounds like chop is not your cup of tea!

However it's the type of condition that develops your reflexes and sailing skills.
You can still find a reasonably flat spot in B.Bay at La Perouse on a good N.Easter in summer.

Rig-up on the grass near the kid's playground and start off in front of the boatshed. After slogging a hundred meters or so, you will be sailing along the beach (namely Yarra Bay on your right). It's a much shorter run than Kyeemagh but you can practise your jibes full speed on ankle-high chop at worst.
Look forward to your feedback
Cheers