Never ever use hot water, that is a good way to crack a windscreen. Get yourself a scrapper, they should sell them in Canberra. You can simply put a small blue cheap tarp over the windscreen, held down by the wipers, just go out and remove it and the frost in the morning. Sun shades on the outside work as well.
The Canadian solution is to buy a car pre-heater, and block heater, which you plug in when parked at home or work, it keeps the coolant jacket of the block warm and will pre-heat the cabin and some incorporate a remote start function to start the car so the defrosters can clear the windscreen.
https://www.lifewire.com/block-heate...tarters-534654