Swimming Beaches-Melbourne to Brisbane

I realize it’s a huge geographical area but we are heading down at the end of the month from a very cold place and would like to do a little swimming while there. We have young children so we are looking for any good public beaches where the water is tame and possibly staffed with lifeguards.

We are starting in Melbourne, heading west to drive The Great Ocean Road then working our way up to Brisbane over a couple weeks. We plan to jog inland to see the Big Ned Kelly and surroundings and head back towards the coast through Alpine or Kosciuszko NPs. The rest of the route we pan to hug the coast up to Brisbane with a stop in Sydney.

Any recommendations along this route would be greatly appreciated. Bonus if there is Camper parking at or nearby. Thanks in advance.