if you want to be able to open the doors, load the boot and walk around i think you need at least 9m x 7m but if you to also want useable work benches and storage spaces (eg for the lawn mower etc) add at least 1 m to width and length

I'm sure there's plenty of confusion about the why's and wherefore's of house orientation. The reality, as I have recently discovered, is that if want to live in an area that is older, developed, close to facilities, you take whatever orientation the block actually happens to be and do the best you can with it. Unless you're out in the country, or buying something in a new estate, you may not get a choice of orientation: we certainly didn't. And yes, our garage does have the best aspect - because there was nowhere else to put it - it had to face the street - but we live walking distance to shops (think of the petrol saved on not having to get into the car), we've got clerestory windows on the west side so no afternoon sun issues, and we're assembling a collection of sails for the south side, where the deck is, to provide shade from the late afternoon sun. Oh, and skylights for the kitchen. No, not ideal. But the location is, and the designers have worked around the constraints of orientation. And that's reality for a lot of us.

keep in mind that my plan has single external walls and all the inside and outside walls are 10cm thick to make drawing easier and the depth of the verandahs includes the eaves, adding a brick veneer would use more space and given the choice it would be lovely to plan for a covered walkway and raked ceilings in the living areas and this is a very basic gable roof but there are lots of more exciting/expensive roof options to consider

You have an ensuite and an identical bathroom around 3 steps further apart. Can't see any advantage for this. You could lose the ens, relocate the WIR and end up with a bigger bedroom, bigger WIR and save money. Your roof has these eaves all close together over what appears to be some upper level windows, but these walls aren't reflected below. If I've understood this correctly you've added significant build cost for little gain. I think the room sizes are ok but I would suggest a design professional to polish it up.