When I had my car in the UK (what an effort, but great fun - see photo!) I also arranged to be issued with an "international driver's licence" via the Australian Automobile Association. They also provided the AUS plate for the back of the car. The international licence just confirmed what previous people have said I needed, that I had a valid Australian drivers licence. It was also supposed to help confirm that at border crossings and if queried by police and was seen to be more authoritative than my Aussie licence which is issued by the state I live in (Australian Capital Territory) which presumably might not be immediately recognised overseas as a legal jurisdiction.