Mate just find an empty field somewhere that's relatively flat, stick up some stumps or a target in front of a fence or something, buy yourself 12 balls, ignore the turn you get as it'll be exaggerated, but work on line and length and get yourself an old car mat and try and hit the car mat. What about your back yard, I thought all you Aussie's had massive yards with acres or space?
I do have a pretty big backyard which I practise a lot in but it's not quite as long as a real pitch and the concrete area I bowl on with tennis balls is quite narrow. Also the Australian weather isn't exactly friendly. One day it's cold, wet, and stormy, the next it is 40C degrees stinking hot with not a cloud to be seen in the sky.