Get travel insurance no matter how long you are going for! and make sure everything is covered. If you are going to be renting cars while overseas make sure the excess insurance is covered on the travel insurance (and remember not to pay extra for it when renting the car).
We got insure4less travel insurance, the contact is in Scarborough Queensland and they are covered by Lloyds of London. It cost us $790 for 3 months.
You need to remember to defer your private health cover for the time of your travel (call them and ask them about it).