Working full time and doing fulltime uni is a hell of a commitment. Are you sure you want to do that?
If you're doing forty hours a week you're not really going to have time to make classes, so you might want to think about external study. However, with external study you usually still have to do the readings and it is a lot harder for frist years because you don't have the class interaction to sharpen your skills.
Have you thought about part time work? Or about coming to uni for a year and getting the hang of it all and then getting full time work?
Or, in case you are wondering, it is possible to survive off centrelink and casual work whilst at uni, just don't ever expect to have spare cash.