welcome to the site sorry can't help with your question but I am sure someone will they are a very knowledgable and helpful lot here on this site. Helena
The drive up Waterfall Way is steep and winding for a good way but not un doable with caution for a first timer.......it is also a very picturesque drive....so definitely make sure you take your time.
Can't help with info beyond Dorrigo though.
When passing through Uralla, make sure you go and have a look at Gostwyck Chapel....you can get directions from the Tourist Info Centre in Uralla
The quickest route from Coffs to Armidale is down through Belligen up to Dorrigo. It is a steep climb up to Dorrigo but only about 10 k. Take it easy and you should be ok
Definitely park your caravan somewhere and go look at all the waterfalls in the area! Some of them are accessable with a van, but Dangars falls was a dirt road and well worth it. (not to be confused with Dangar falls)
As others have said, the climb up Waterfall Way is pretty steep, just take it easy. The drop down again through Kootingal to Tamworth is also very steep, stay in low gear to stop the rig getting away from you. This part isn't as windy (as in curvy) though. Just remember YOU ARE NOT IN A HURRY and you'll be fine. We've taken our van both directions on this road quite happily.
Enjoy the drive - the Waterfall Way, particularly just out of Dorrigo, is a spectacular route. There's a really nice rainforest centre to stop at just before Dorrigo (about 1500m before you get to the town) and quite a few waterfalls after Dorrigo - as the name Waterfall Way implies.