In Sydney, the major universities offer a MA degree in Visual Communication, Design and Multimedia. There isn't a degree which specifically focuses on Illustration but you would most likely be able to choose to do the subject.
The important thing is to find the environment you feel most comfortable with. Did you want to progress in Illustration fine arts based that also involves work including textiles, ceremaics, painting or Illustration for contemporary magazines, graphic magazines, newspapers? I think the latter would mean choosing a MA in Visual Communication which is similarly MA Comm Art & Design offered at RCA London. More over, you could consider Konstfack University in Stockholm or even Yale's MA programs in U.S.
Get yourself in touch with UNSW or UTS or other universities you may want to study at by phoning them or come down to Sydney. Check out the different online universities' websites too.