Thanks to JimJim for suggesting this route. The walk was really spectacular, I would highly recommend it and I expect I'll be back to do the remaining part.
Day 1
Castle Cove Lookout to Johanna Beach. 7km
A nice easy start after the 3hr drive from Melbourne to Princeton where I dropped the car off. Its a grisly opening shot, but I found a dead dolpin just south of Johanna Beach.

Johanna Beach walk in campsite is a good spot with nice sea views from the tent.

It is easy enough to find Johanna Beach campsite as long as you take the new route that starts not far from the Johanna beach lookout. There is still a sign for the old route at the gate further down the slope - this leads you in a more circular route and it can be more difficult to find the campsite from this direction.
Day 2
Johanna Beach to Ryans Den. 14km
Spectacular scenery just after Johanna Beach campsite


Ryans Den campsite was fairly average after the previous night, although a nice lookout.

Day 3
Ryans Den to Devils Kitchen. 13km
I cut it close with the tide at Wreck Beach, the waves were coming up quite far.

but well worth heading down this way to see the wrecks

Day 4
Devils Kitchen to Princetown. 7km (?)
Devils Kitchen Campsite is great, but only site no. 8 has a sea view so worth getting in early to grab it. I managed to lose the Great Ocean Walk track just after leaving the campsite. Annoyingly I ended up on the Old Coach Rd all the way back to Princetown. It was a nice enough walk through farm land, but I was annoyed to have missed the GOW path. Its worth keeping an eye out for the signs at this point so you dont make the same mistake.
The weather was pretty awful on the final day

... so I skipped the final leg to the Apostles this time (I had already seen them anyway...).
This was my first solo walk and I thoroughly enjoyed it. The lack of company wasnt really an issue at all until the evenings where I'll admit I was pretty bored at times. There was one other couple on the route but they were in their tent by 530pm each day, and I only had phone reception from my tent at Ryans Den. I finished the small amount of whisky I had on the first night, in hindsight I wish I had taken much more. Ive also watched far too many horror films, I'll admit that being in the woods on my own at night did affect me at times(!).