rosequartz- your licence is no longer legal after one year living abroad, as well as when address has not been changed to your current legal address. Not sure about OZ- but in Europe you have to take your licence to the equivalent of the DVLA in the country you are living- and your licence will be exchanged for a local one, your UK one taken away and sent back to DVLA. You can rent a car on a foreign licence (some age restrictions) but you can't have a car registered in UK and insure it if you do not have permanent address in UK, and not just a relatives or holiday address.
Again, not sure about regs with OZ, but I am pretty sure their UK licence should have been exchanged and returned to DVLA. Does anyone have a link to that effect (or exception clause for OZ).