This just happened to me, too. Almost same situation, but im in the usa. I moved to Chicago, which is probably fairly comparable to Sydney (Big city, lots of diversity, stuff to do, ect., maybe a bit tamer with it being in the midwestern usa and not a coastal city)
I won't sugar-coat it, it's tough. Just about everything I do out here is by myself, although in a major city, it's not hard to find people to talk with (small-talk, anyways). And when my loneliness becomes unbearable, I go out and try to do something fun (again, easy to do in a big city), or call family or friends back home (talked with one of my buddies for 2 hours once, rare for a guy). But on the negative, my close friends are not close at hand, and being nervous around people, its tough to find new friends, although the move has made me become alittle more outgoing (although still not where I wanna be).
What I'm doing to try to solve my problem is to think positively and try to reason with the voice in my head that likes to put me down, and am starting therapy. This therapist is better than anyone I ever saw back home, he pretty much nailed my situation on the head! So I think with enough time, the move to a bigger city will help me grow more than I could have back home. Lonliness is a powerful motivator, sometimes it is a stronger emotion than the fear of talking to new people, also, a bigger city has more to offer in the form of help than a smaller, more provincial one. People also tend to be a bit more open-minded, too.
How far is Sydney from the hometown? Will you be able to get back home easily (you will probably want to have face-to-face contact with old friends and family at least once a month).
I give you (and myself) lots of credit for making such a bold move, I think if we're strong enough to do that (a lot of people WITHOUT sa wouldn't be able to do what we did), I think there's hope for beating this fucking disorder! Good luck, and keep us posted!
...i don't have any advice for you on that...sorry 
