Yes, You can drive legally.
Your Australian driving experience will certainly help since both drive on same side. Traffic congestion can be a problem depending upon where you are. So it’s not like a piece of cake. People don’t really recommend tourists drive cars in central London but we don’t really know where you plan to drive.
If its going to be London, I would also recommend avoiding a car. Its just too much cost and hassle for not too big of a benefit. TFL is great and you are never too far away from a Tube station or a bus stop.
In London 3 things are all you need. Oyster Card, City Mapper and some £s :P