I've been fortunate enough to be working on a really intense project the last few months as basically the Project Engineer on the job. Basically they were booking all their time to the company overhead and they got the awful tap on the shoulder and said it was time to go.
However, our project finishes officially at the end of May. However, there may be some follow up work after the project is finished. But you know, in today's climate you've got to expect that someday it'll be you who gets the news.
So take what you can mate, even if it is for a short period of time. You'll be a lot more sought after with that international experience. What does your girlfriend think of all this? Would she come along too? How about your parents? I mean Sydney and Melbourne is not a big move, but London is a pretty huge move.