Be aware that Flightwatch are a messenger service, they can't give you clearances and traffic information directly, they just relay that information from the relevant centre controller.
And THAT is what a lot of people don't understand. They're even in separate buildings (or States when you're talking Melbourne Centre)!
Flight watch is manned by AusFIC (Australian Flight Information Centre I believe). They're also the guys who ring you up when you've buggered up your flight plan, and even issue the NOTAM's as well I think.
It does amaze me the number of students who leave their flying schools never having touched a HF radio (I was one of them!), some don't even know what one is. Yet it's such a vital piece of aviation infrastructure in Australia, because of the vast outback areas that simply could not support a huge network of VHF transmitters.
I remember doing mail runs in the Tanami Dessert, where the only times you'd hear something on the VHF radio, was departing or arriving Alice Springs. The rest of the trip, it was very lonely on the radio, or you were talking to flight watch on the HF.
morno