Some good comments above. My simple suggestion goes like this. Starting at each end, I see they are adjustable, double up the shelves making them stronger, and then you will only have two shelves in each bay. Even them out so yu end up with three equal cubbies. They will look quite cubed, and house foldable fabric baskets which are cheaply available in many colours, try Kmart for packs of 5 for less than 10.00. I would use these end cubes for your practical needs, like onesies, singlets, nappies and creams etc. The central shelves I would display the children's favourite things, on lower shelves, books to access, and some things you want seen as keepsakes, not to play with a they won't reach them easily. The shelves could be configured differently in each space depending on use, but I'd utilize the lower two cubes in one room as desk space, with books above. A cute colourful lamp, and again foldable baskets each side, so that perhaps each child may choose their own side, and have somewhere that's just theirs. In a house ful, it's even more important to have somewhere just for your stuff. These will be great when you make them a little less busy, and providing those inserts will keep them looking tidy, even when they're not. maybe you Could have different colours for each child, to help with the order of things. Good luck with another bub.

Don't put in a false ceiling. Raked ceilings are lovely and that extra air space in a bathroom is a big bonus. If I'm reading correctly, your showers are on the high wall, so logically taking tiles to the standard 2100 height would make sense. Your could choose to continue at that height all the way around, or drop to a lower height outside the shower area. It's a matter of deciding what look you like. You could, for example, change the wall covering outside the shower area to make the shower a feature. Use a feature paneling elsewhere, for example. Run a dado rail around outside the shower and tile or panel only up to the rail. Or use a feature tile over the basin and tile only up to the mirror or medicine cabinet. I used to be with Kate, hating tiles to the ceiling, but we just had our bathrooms redone that way and I love them, but we added interest by using a 2100mm wall in front of the shower with a feature black trim top and using the floor tile for contrast on one wall. We had tiles to the ceiling before the reno and I hated them because they were bland and uninteresting so the whole effect was drab. We took care to replace them with tiles that pop a little, and trims that stand out, and feature marble vanity basins so that the eye is drawn to a feature as soon as you enter. I don't think the tile height matters nearly as much as choosing the right tiles and accessories and creating a look that catches the eye immediately - go for a wow factor somewhere! It might be the vanity, some feature timber trims and vanity cpd doors or dado rail, or some interesting shelving over the bath. Co-ordinate with care and the tile height won't matter a jot.

I keep coming back to this plan. If it was drawn up by a professional they need to give the money back. EG There looks to be about 50cm between the shelving in Bed2 so I hope the child using that room is small and stays small. The double front door is shown with the hinges in the middle giving two adjacent doors not a double opening. Most of the doors are jammed in on the plan and the doorknobs will go through the walls. The main bathroom layout wastes space with the shower being big standard when for minimum cost, it could be 1200 and way nicer to use. The roof line is a mess. Apart from the issues others have raised. If the Poster didn’t have pics in their lookbook I’d think this was a homework question.

Thank you @Julie Herbert, we've decided to do the diy thing with trim around, that was a great idea. But yes, great point about boys using the mirror to do their posing when they get into that sort of a thing 😁