Hi Corrie,
There aren't any Australian job fairs, but the recruitment page is here:
http://www.aad.gov.au/default.asp?casid=23915
There is a call for qualified doctors in Antractica, but not for nurses. People who go down have to have a rigorous medical and be in good health. Disease-wise it is generally a healthy environment so people rarely get ill, though accidents happen of course. Doctors therefore have little actual doctoring to do, but tend to spend their time involved in a research project.
If you are looking for a job in a polar environment, the arctic is going to be far more likely to offer what you are looking for as the arctic has settlements with towns and cities and so hospitals and nurses to staff them.
Good luck.