UK is the same in urban areas so you are not on your own regards back yard plinking, I have a couple of permissions but liked to same farmer. It will take time and you may be turned down more times than you hope but it only takes one yes and you are on your way.
I have just begun to set up a small HFT practice range in a small wood I can shoot in, but it has taken me about 18 months to get to this stage.
Why not try looking up local HFT clubs I know you guys down under must have them a world championship was shot there a year or so ago.
Welcome again and good luck.