Q about Australian English

I don't know is there any main difference between UK and AU English?

No much, the slang used are different. So some words may have a different meaning and usage.

And also the accent, can anyone please briefly explain how to speak an Australian Accent?

Australia is as big as China, so their accents differ from place to place. If you live in a city, you wouldn't notice much, the more away you are from the city, the more accents you would hear. Don't worry, you will pick up the accents as soon as you settle down in Australia.

If you want to be more prepared. Here is a online radio station you can turn in. It should help.
http://www.adonline.id.au/radio/

2012-03-15 15:53:59 補充：
Exactly

To-die is vary hut.

Thank you for a vivid example.

Ya, "to-die" is very hut! 今天非常熱