Hi there - a few things stand out to me... yes keep bedroom sizes no less than 3000mm wide, offset the door to the laundry so you can't see the toilet from the front door - yuk! Minimise/simplify number of piers by turning front porch 90º. Keep the footprint as simple as possible. With oklouise's plan, which i think makes more sense, cut 300mm into each of the bedrooms and push out towards the left into the deck. Much better use of space. If west is to the left put a whole wall of cupboards along in bed 1 and get rid of the others, and add door out to deck on the (new) north wall. Do you really need a bath? Living in country they are wasteful of water even if it goes back onto your land. Alternatively have a combined shower/bath? Babies and toddlers wash quite well in the laundry tub then learn to shower with you or on their own quite happily. I'd make the shower a big bigger (and the cupboard on the hall side) and get rid of the bath. Make sure you have excellent insulation in walls, ceiling and under floor. Consider hebel panels as flooring (also, the reinforced ones span great distances) and walls for both fire safety and insulation value. If possible look for ramp potential in case of disability and also for getting furniture into house. If you're in a fire zone make sure all windows and doors comply with your zone rating. And if you are building high up on piers make the external cladding is something that never needs painting and is minimal maintenance.

we have tiled over a wall that encloses a cavity slider by adding an extra layer of reinforcing to the internal wall that also allows for installation of grab rails that double as towel rails..we chose a solid core door and extra heavy duty tracks and the door slides inside the tiled wall with very little sound but, to allow for the extra reinforcing panel, the wall is 125mm thick excluding the architraves

@HU-319610855 I’m not saying this to be even the slightest bit contradictory, so please don’t take it that way. We had seperate everything. Doors, walls and divisions everywhere. We pulled it all out and went combo. We‘ve never had an issue with conflicting use, and we love the feeling of extra space and openness it created. I’m sure it all depends on your household. :-)

Save big money on importing one from the UK and spend it on design to make the space work for you without the need for such an impractical solution. There are some cute, tiny wall mounted hand basins which would be a neater solution. https://www.reece.com.au/product/basins-c448/wall-mounted-basins-c452/axa-cento-mini-wall-basin-right-hand-with-fixing-1-9505814 If there is no other option here is another type of toilet/handwash product, but I don't think it looks any better than the Caromo design, although overcomes some of the impracticalities mentioned in the previous comments. https://www.reece.com.au/product/basins-c448/wall-mounted-basins-c452/roca-w-w-integrated-washbasin-white-5-star-9505427 Best of luck, Dr Retro of Dr Retro House Calls/Dr Retro Virtual Visits