Hi Brian
Sutherland Astronimcal Society (SASI -
www.sasi.net.au) has a junior section which meets on the third Thursday of each month. The reason I mention this is our club has a semi dark site down at Waterfall in the Royal National Park. The club observes from there on the Saturday nights of the third quarter and new moon.
Your daughter will also meet other children her age who have an interest. I honestly don't know how the course runs but I am sure an email to our society will answer any questions that you may have.
Dark sites close to Sydney are rare. For a great dark site I can recomend Wollondilly River on the Wombeyan Caves Road. Drive through Mittagong, where the on ramp goes back on the highway at the south of Mittagong take the branch off to the right (the old Hume Highway). There is a right turn a couple of kms down the road to Wombeyan Caves. Wollondilly River campsite is a fair drive along there. It is rough bush camping but it is pretty cheap and the skies are inky dark.
I hope that insight gives you some assistance and I sincerely hope you and your daughter enjoy many many years under dark skies together.
Wayne