Hi Simon,
I'm not sure if this helps you. Last year I stayed in a great guesthouse with its own observatory. It was fantastic, I really enjoyed it.
http://www.twinstarguesthouse.com/
It is however a quite a distance from Melbourne. It is a little under 3 hours drive south west of Brisbane, or about 9 hours north of Sydney.
That being said, I can really recommend it. It has wonderful dark sky's and a fairly good setup.
I hope this helps.
Earl.