Free or heavily discounted medical for civilians is slightly complicated but still better than the NHS. Theres a medicare-surcharge to cover it. Defence members are exempt the 2% levi initially each year but you may get a reduced tax refund or a bill at the end as some will be clawed back by ATO to cover your partners med contributions liability depending on their earnings and private health cover. Aus citizens are encouraged to take out private health cover on top, in doing so their levi may be reduced further.

Some tips:

• If you are posting to Darwin, dependants registered with veterans medical group near the CBD can get 100% back every time through adffamilyhealth.com and their medicare-rebate even if they used their $800 ADF annual allowance. (Not including prescriptions)
• The use of bulk-billing facilities in all states can work out to be free
• Dental tourism is becoming popular, you can go to Bali or Thailand, stay in a 5 star hotel on the beach. While there get treatment much cheaper. The total cost including treatment, flights, accommodation, food and drink can often be less than it would just getting the treatment in Melbourne, Sydney or Brisbane. (Maybe use an RLLT towards a holiday and get treatments while there)
• Defence health and navy health offer defence family discounted policies on private cover. There is usually a rep at the new Lateral welcome days to discuss your options
• canstar.com.au/health-insurance is a helpful comparison site

I hear if you plan to have children in Australia, it pays dividend to have private cover to ensure the best treatment and private room post labour. Talk to other new mums on your arrival about the vailidity of this claim

Warning! I have also heard more than one tale of private health not delivering the right or agreed cover for dental. Often charging for it in peoples 1^st few years of policy, then stating it is not effective until 2^nd or 3^rd year when a claim is made.  Read the fine print!