There’s plenty of people asking “Which Server?” questions. Usually the answer is here:
https://www.guildwars2.com/en/news/introducing-the-megaserver-system/
TL;DR: Unless you’re into WvW, it doesn’t matter which server you are on.
You can find an Aussie guild on the Looking For forum – I’m pretty sure I’ve seen a couple, at least. From then on, it’s luck!
Good luck! 
EU The Right Trolls ~JiVE~