Theres a heap a nice places to potter about on the coast. Crowdy Bay National park is just one. Point Plomer too.
Why not plan on doing the Great Ocean Road whilst your at it. 6 weeks is plenty of time, and if you don't mind a bit of driving easily doable.
Heres a quick itinerary for you:
Leave Brissy, drive for 6 hours, that should see you somewhere in the vicinity of Port Macquarie. Stop for the night.
Next morning get your skates on and drive to Canberra. Stop for 2 nights and see the sights.
After you've had enough of war memorial and national galleries, hitch up and head off. Next stop Warrnambool / Port Fairy. Stop.
Spend a few days mooching up the GOR to Torquay. Yes its better to travel the GOR from east to west, but really only along the "cliff" section. Find a good spot to camp and take your time. The Great Ocean Road is only about a 3 hour drive anyway.
From Torquay head up towards Beechworth and its surrounds. Kosciiuszko National Park, Jindabyne, Lake Eucumbene to name a few other spots. A few days in and around these parts then hit the south coast. From Eden up theres a a lot to see.
Mooch up the coast, bypass Sydney, then continue up the coast.
You could achieve all that in 4 weeks, 6 easily.
Start googling ...
