Update here. I've kind of worked out a solution for this, feel free to chime in on your opinions. So with summer approaching, I decided to take the plunge and install a concrete slab with 1 of these 3x3 shed at Bunnings warehouse;
https://www.bunnings.com.au/absco-sheds ... d_p0079534 ;
https://www.bunnings.com.au/pinnacle-3- ... d_p0080616 ,that comes with installation for only 179$, which I'm happy to spend. (concrete is only 499-500$ range).
The driveway I mentioned has the uneven slope, but at the top where the gate is it goes in further:
Then this is what is after:
It's a narrow workspace, but I will have to compromise. I threw out the idea of installing a garage, as it's going to cost over $5000+ for the entire kit, excavator, concrete and labor. Only issue I'm looking at is an uneven surface as shown by the level.
Thinking of concreting the middle part where the grass is, clear bins etc. then that could be a solid workspace. I won't be able to concrete the sides, as the fence is too close to my neighbours, and the other side has drainage and air conditioning wires dug in.
Kind of a poor compromise in workspace but I'd rather this then working on a slope any day. Will update as the installation progresses.