Drive down the south coast Highway past Southbroom and take a left at San Lameer Holiday Estate. GPS co-ords will roughly take you too the area, but you shouldn't need them.
Can be good, but probably not worth it with all the hassles, try Glenmore beach further south.
General
San Lameer is a rich mans resort/estate, so if the bloke at the gate gives you trouble just act rich and make up an excuse for your racked surfboards. Just be chilled and act like you know where you are going through the estate and follow the beach signs. Haha enjoy :)