If you dont want to do that you can apply to TRA and get the ARTC cert. This with the wiring regs course = no working as a trades assistant for 12 months. You get your A class licence straight away.
You can apply to the TRA from the UK but the wont post the cert to you in the UK, you get that when you get to Aus. Cost $300
You can enrol at PEER for the wiring regs course from the UK to start the course via distance learning. They will accept any applicants as long as you hold a OSTR or a ARTC cert. Cost $1500 approx.
Once you have a ARTC cert from the TRA and the wiring regs cert from PEER its straight to energy safe and get your A class.