This is one of the most beautiful and popular stretches of road in the country. There is public transport to major centres along the road but the only way to really see this area is by car. If you don't have a vehicle look for a group to join or rent a car for a few days. If you are in Melbourne it is possible to drive it and return to Melbourne in 1 day but you will feel a bit rushed. From Me ..
Great Ocean Walk There is a walk that links the coast here and essentially follows the Great Ocean Rd for 100km. Obviously this walk takes a long time and requires a lot of planning. There is also the Surf Coast Walk from Torquay to Lorne. Lots of great campsites along the way and you can choose to do only a section of the walk.