The newly-launched and government-backed MyBroadband site is designed to offer an indication of the broadband options available for a particular address. However, you can't actually trust what it says.
The site is easy to use: type in an address and it will show you whether ADSL, cable or fibre services (NBN) or otherwise are available. Before you see this, you have to read through a warning which notes that "The ratings that are about to be shown are indicative only and may not reflect the actual speed of the specific broadband service for the address entered."
This is something of an understatement. For my home address, the claimed typical ADSL speed was much higher than it ever actually is, and it claims I have 4G coverage when I don't (on any network). For a friend's house, it claimed HFC was available when it isn't.
What makes this worrisome is that the same data that powers this map is being used by NBNCo to plan its revamped network, in which existing infrastructure is supposed to be used whenever possible. If the assumption is made that your address offers HFC and it actually doesn't, it's hard to see how you avoid being screwed.