poleonpom, there is a place called Daley's, in Leo St Fawkner, who supply headliner material as well as the proper adhesive spray cans. Daley's - Home
They let me into the factory to show me what vehicle headliner materials they had, so I was able to hand pick the one I wanted, which was a dark charcoal colour, but they do have pretty much the original headliner colours there as well if you prefer that.
I think it is a standard thickness, foam backed material, but you would be able to check it out for yourself.
I got 3.5 meters, which left a little bit over after doing the sunroof...better too much than not enough!

