If you really can't leave Perth I'd say for the first year or two your options are solely instructing. I don't think any of the Perth charter companies take 200 hour pilots (who aren't also instructors to work in their flying school). If you can relocate your family further North you'd open up your options.
Wage of 30k? At best. It really depends, some people go straight on full time and earn more, most spend a year or two (or three!!) on casual and would earn that, sometimes less.
I have a lot of respect for the guys who do GA with a family. I found it hard enough to support 1 single person let alone a whole mob!