I am Stuart Williams-Ley, a staff member at Cedarwood Sudbury School in Santa
Clara, CA. I don't think that returning to school would make you any better
prepared to work at a Sudbury school. To pursue this ambition, you need to
either move to where a Sudbury school is located, or help start one yourself.
As you say, moving presents a challenge. At the same time, starting a school
requires tremendous effort, and I have no idea whether starting one in
Australia would be more or less daunting than in the US. Sudbury Valley
School Press has recently published a book on starting a Sudbury school that
might be interesting reading for you.