Watch "Home and Away" and "Neighbours". You can find old episodes on youtube.
The problem with most language lessons is that the teacher will often modify their language to match the students level so It pays to be exposed to authentic content.
There are a lot of contractions you'll need to get used to e.g. Brecky = Breakfast, Maccas= McDonalds. Googling "Aussie slang" will help.
Also searcing the terms Wogs vs Aussies, bogans, Lebs vs Aussies, skips, housos, Fat Pizza, Kath and Kim. These will provide you with some particularly Australian expressions.