This organisation provides surfing oppurtunites for all people and all abilities. They operate along the East Coast of Australia, and a few other locations. Bear in mind that the ones in Victoria are all at least 1 hour from Melbourne, so you may want to determine your best option for getting to those locations.
That is so awesome! I am always so excited to hear stories of how people are smashing down barriers and coming up with unique ways to help make leisure and sport open to everyone regardless of disability.