You could reverse the layout of the ensuite, and have the door to it through the walk in wardrobe (so you would only have one door coming off the bedroom). If I were you, I'd consider swapping the positions of the ensuite and wardrobe, so the current ensuite door becomes the wardrobe door. That way you could move the bed to the east (right), and you would have room for a seating area in the north west corner of the room (as your bedroom looks huge!). I'd also add a window on the small bit of north facing wall in that room; you already have corner windows in the living and another bedroom, so you could match those in style. Personally I don't particularly like the current layout of the main bathroom, although I can see the reasoning behind it (i.e. vanity at entrance, toilet hidden behind wall, window above bath). I think it might work better if you put the shower in the corner where the bath currently is (i.e. beside the toilet, opening to the west), and the bath on the same wall as the vanity. You'd have to move the window, of course. Alternatively, do you actually need three toilets? You could remove the toilet in the main bathroom, and you'd have room for a freestanding bath and/or a bigger shower. You could consider stealing a bit of space from the kitchen to create some storage at the entryway. I'm not sure where your garage will be, but it's really handy to have a designated place at the point of entry for all the stuff you tend to dump when you first come into the house (schoolbags, coats, mail etc). Overall, I think the layout is pretty good, but you could potentially lower the build cost by making it all a bit smaller. It's really worthwhile taking the time to figure out just how much space you actually need, and where you need it. For example, if it were my house, I'd take about half a metre off both the east bedrooms (so the house is shorter from east to west), plus I'd make it smaller north to south by slightly reducing the size of all three bedrooms, and making the kitchen a bit smaller (so the hall cupboard lines up with the back wall of the small living room). But your priorities may be completely different from mine!

I agree you probably need to centre the vanity and the cabinet on the wall or they could look a bit odd! You don't say why you don't want a space between the window and the vanity - just my opinion, but I would think 300mm could be quite useful for a bin, a clothes basket or box, or a small stool for putting clothes on? The only alternative to leaving a space, is to fill it with something as the response above suggested. To avoid it interfering with the window, you could make this something lower, so it sits level with the top of the vanity. This could be built in and the wall lining put over it to create a single "shelf" level with the underside of the vanity top, or if you can find some freestanding open shelving of the correct width, which could also be cut to the correct height, you could wedge that between the wall and the vanity side when fitting the vanity. Just bear in mind also, that you'll lose some of your towel hanging space if you put something too high in the space.

always prefer separate toilet with handbasin, the bathroom has plenty of space for generous fixtures up to the sizes shown but the bathroom should be planned to suit potential users and relative to the whole plan (where are the windows?) next door rooms, orientation, outlook etc...this is one suggestion that has the best view on entering the room with the shower (tallest) at the side, bath with potential view, vanity with option for two basins and matching mirror doored wall cabinet and the toilet handbasin next to the shower keeps the plumbing sounds away from adjoining rooms more details may inspire other suggestions

Will need to see layout to give opinion. Doesn't look like a free standing tub is a good option for you but if you show us the layout we can give you an accurate advice.