Ideally you want only 1 bossy / busy fixed element. At the moment you have lots going on with the mosaics and the wall tiles and a mixture of undertones. On the whole granites and marbles also demand to be the centre of attention which is why I would suggest you select a very plain countertop. You'll probably find a few which are well within the granite/marble price bracket. Decide which is the largest visual undertone and use that for the countertop.

Hi. I think any dark, rich colour could work well (would paint the skirts in the wall colour) but if you didn't want to paint the furniture either a really deep teal or inky blue would work well. Perhaps use ochre or burnt orange as accent colours or moss or emerald/grass green work really well with an inky blue. I assume the ceilings aren't tanked so you'll need a ceiling fix pole? Having floor to ceiling curtains will make it feel taller. I'd also have a tall portrait leaner mirror on the wall opposite the window to make it feel taller and to bounce light (do you know where the stud work is for attaching things to walls?) Could you have a light weight canvas hung on the chimney breast attached with those sticky pads? Agree re lighting and would also add 1/2 floor lamps. Is an electric stove in budget for the chimney? My only reservation is dark walls against a white ceiling. I think my basement is the same height and I deliberated for ages and in the end painted it all white :) there is an argument that dark ceilings can create depth as you can't see where they end.. also an argument re white gloss or Matt finish for the ceilings! If you did go for dark walls though i might consider a mid shade for the ceiling

As Jonathan says, you start with the Soil pipe, and if you've agreed with your bathroom fitter that he's able to put the pipe across the wall behind the toilet and under the bath to get to the outside wall, then that's fine, but if not, you really need to discuss it with a professional. There are many reasons and regulations that you need to stick to with regards placement of soil pipes, because sometimes you need access to unblock them. When designing a bathroom, it is important to know where you have to have some items and then decide where you can put the other items that you want. Check the soil pipe situation as this dictates where everything else can go. I suspect unfortunately, that if you can't solve the soil pipe problem and the toilet needs to go on the outside wall ( which is the normal place for it ), then you may have to have a re-think and possibly change what you have purchased. I've tried to have a re-jig with what you've purchased and moving the toilet to it's normal position, but i can only make them fit if you do what Jonathan suggests. Even then, I would suggest that the door be moved along the wall to accommodate the tall unit. You will have pipework from the vanity that you need to box in, it can go under the bath, but at least it's just water not the soil pipe. I would have also considered a bath to fill the whole gap of 2000mm not a 1700mm, but you can use the gap to build a space at the end both covering the pipes and giving you somewhere to stand toiletries. The taps for the bath aren't marked, so i'd probably put them on the bottom end nearest the vanity on the flipped plan below.

I think part of the problem is the divide at the same height as a dado which makes it feel very old fashioned. Also because these tiles are different sizes the joints will always sit uncomfortably against one another on the same flat wall. What I would do is tile the majority of the bathroom in the plain tile then have a vertical stripe of the patterned tile that starts on one wall, crosses the floor, then goes up the opposite wall- the strip should be bordered with tile trim so that the joints are separated. Alternatively just tile an accent area with the pattern such as the floor or one wall in the shower