It's not uncommon to feel anxious during such events and it is stressful. However, some things might help you.
Contact any friend that you might have in Australia and query him about the place, food, living situations, etc. If you do not have friends in Australia try to contact associations (any Indian association - search the web) and get more information OR if you are going to a specific company or school, contact the particular company / school and ask them if you can talk to someone from your background.
Write down the things that you are concerned about (e.g., who will cook for me! how will I deal with people over there, etc) and then search for information - from web / other information sources. From friends/family and write down next to the question. Be as objective as possible in your answers. Write any and every question that might pop in your mind. Once you do this assignment thoroughly it might itself relieve your anxiety / stress to certain extent.
Also talk to your friends / family about how you feel currently.