Not really sure, you could ask the Aussie Embassy as they will have Mil staff there that could answer your questions.
I know of two who tried it. First was an officer and he sailed it, straight into a unit with same rank and I think was allowed to keep his time served in rank as well. He had EW experience and went into a new unit they were forming.
The other was a senior Cpl and was messed about, the unit he wanted to join wanted him and helped him, but the Aussie Army decided he would have to do basic and trade training again and start from scratch. He also would not be guaranteed a choice of units once he passed. He told them to Eff off.
Generally speaking when you transfer to the ADF (aus defence force) you keep your rank, seniority etc etc, you may have to go down to a place called Kapuka for a cut down version of basic training but not sure on that one, you will also have to agree to become an australian citizen although you wont be required to relinquish your uk citizenship as aus supports dual nationality.
If you want any more gen PM me and I may be able to get hold of it or a contact, there are a fair few brits how have made the transfer in the past...