Hi Skipd here's a couple of spots to get you started.
Black Arrow - Harding Rd is where the GPS sailing happens in an Easterly. Weed fin is a must, can need quite small sizes as well during Summer as tide is lower, think 25cm and under.
Yellow Arrow - Chipana Dr is often used in an Easterly by the B+J sailors. Find the Yacht Club and there are 2 houses just West of there, next to the 2nd house is a little area where you can park & rig. Probably still need a weed fin especially if staying on the bank which is a few hundred meters long before dropping off.
White Arrow - Quaranup Rd can be sailed in Westerlys or an Easterly if the tide is high enough. Go past the Winding Rd sign & as the road straightens again there is a turn off to the left. If you have a 4x4 you can park on the sand if tide permits. You'll be rigging on sand, seaweed, gravel or road verge depending on conditions.
You could probably also look at launching from the West side of the Entertainment Centre. That's just Princess Royal Harbour some guys sail in King George Sound if you want a more open water experience & Oyster Harbour is also sailable.
If your looking for lifestyle blocks then Robinson is close to Town & Harding Rd or go a bit further out to somewhere like Elleker for bigger blocks.