This certainly lokks like the larva of a Limacodidae species, but it does not resemble any of the larvae of the 20 Limacocidae species illustrated at http://lepidoptera.butterflyhouse.com.au/lima/lima-cats.html It does not resemble the Pseudanapaea larvae shown there, as those larvae have no stinging spines. It is probably the larva of one of the other 96 Australian Limacdidae species. @clarehoneydove : I do hope you can rear it in protective custody to get an adult moth to ID the species.
On second thoughts, the thoracic shield does look like that of Doratifera oxleyi, which does have variable colours. I am thinking now that this is D oxleyi.