All versions of the English language are essentially the same and people from countries such as US, UK, Australia, New Zealand can all understand each other very well.
The only differences are the accents which identify where about you're from. The language is just as clear to each other, but the slang is different from country to country, and region to region within each country. Since Australia is a multicultural country, only farmers in the remote areas of Australia speak with a broad Australian accent.
Aside from that, certain countries have a few different words for things like UK say pavement where in the USA they say sidewalk. UK say tap and US say faucett etc.TV shows from these 2 countries will teach you all that. If you have the TV series Home and Away in your country, you can listen to Australian accents.
Australian English is much closer to British English, than American, but you should have no problems understanding the language itself.