RV tour from Brisbane QLD to Manly NSW ??

Hello Kim
Firstly , there are plenty of campgrounds , caravan parks , National park camping places .
Mostly they will require some notice , but a phone call should be sufficient in most cases. National Parks will require booking on line in most cases.
There are a lot of people using caravan parks and camping areas , so be warned that availability is not guaranteed along the east coast. A phone call around late morning might be advisable.

It's a lovely coast so have a great time.
Cheers
Jim

Thank you... that's very helpful...

If you go after the school holidays, you should be OK for drop in camping. You may find some parks booked out, but there will be others nearby or in the next town.

Thank you... this is very helpful

The coastal route from Brisbane down to Sydney is very popular as are the numerous popular commercial camping sites and to be mindful that you will have to get off the M1 and journey to these camp sites.
Free camps are available, but you will have to get in earlier during the afternoon for the more popular ones because they have become well known and can get crowded.
The National Parks have upgraded many of their parks along the coastal strip and are easy to get to with a RV, again these can be popular with migrating campers moving around.

You'll have plenty of options to stay at along the coast, just makes sure you book them as soon as you have your itinerary sorted. The top locations always book out well in advance.

l came across this site which l found very helpful with my travel plans. https://www.drivenow.com.au/campervan-hire/handbook