By my calculations your changes leave you with a shower that is 660 wide. Very narrow unless you’re a stick figure. I also wouldn’t be aiming to keep the wall tiles, you are doing major movements and keeping tiles may be false economy.

Sorry I read the plan wrong. You seem to have 900 less the width of the wall which is still tight.

Thanks for your comments, bigreader. Assuming a 600mm wide vanity (and generally they seem to be a bit less), it seems to me we could have a 900mm wide shower (x 1800mm long, so quite large overall), and still have space for the wall and about 1m in front of the vanity. I wouldn't want it any tighter, but I feel it should be okay. The wall doesn't need to be 70mm. It could be quite skinny as it's only a partition. I'm just concerned that the door might be too close to the vanity and an obstruction if left open when using the basin.

I thought 900mm was actually a standard shower width?

I did think about removing all the wall tiles but it's a huge task to remove them as they are stuck incredibly tight (not your usual tiling job!). We removed some tiles from a kitchen wall in this house and we actually had to cut the whole wall lining away because the tiles wouldn't budge! And then there's the cost of disposal. Given that they are in excellent condition and top quality tiles, it seems to be unnecessarily wasteful to take them all off. Wetwall sheeting can go right over them in the shower, and if the right design is chosen the partitions plus a stylish vanity should be enough, I think, to compensate for the blandness of the tiles. They are not actually ugly. It's just that there's way too much of one very bland colour.

the arrangement looks like it should work for the shower with a dividing wall tall enough for mirror wall cabinet but the vanity cabinets should be no bigger than about 1700 x 450 to allow for more passing and standing space and consider having all the new walls the same height to allow for a doorway into the toilet and shower and the tall storage (with or without a door) accessed from inside the toilet room not the shower space

Thank you, gurus oklouise and siriuskey. Your knowledge and ideas are invaluable.

oklouise, I could live with 1700 x 450 vanity and storage opening from inside toilet room. It would just mean I'd have to sell the marble basins I purchased months ago and find smaller basins. Not really a major problem if it achieves the end goal!

siriuskey, I did consider this arrangement (but with the shower the existing width), and would certainly be an improvement on the existing layout, but I really prefer the toilet being separate. If I stick with this arrangement, I'd have to at least lengthen and raise the height of the small privacy wall. The impact of moving the door on the adjoining room isn't significant. It just means I have to rearrange furniute in a way that isn't quite as appealing.

I think it will come down to comparative costs. I know the alcove arrangement will be a lot more expensive, but I do like it much better so it will depend how much more expensive. Leaving as is and moving the door will still require major work to the floor in the shower area, but narrowing and lengthening the shower will achieve my major objective of eliminating all the glass. (Odd how you can get tied up and miss the obvious when planning! I hadn't considered the benefit of narrowing the shower while lengthening. That does make a big difference!)

At least I've now narrowed it down to two options so I can proceed to get some cost estimates. Thanks again.

the major challenge will be sloping the floor but a glass door and floor track into the shower room could make that easier and, despite 90cms being the normal width of a "standard" shower the shower space could be slightly narrowed (we've successfully used 60cm x 120cm) and the bathroom entry door could be narrowed to 75cm to steal a littele extra space to save your basins and consider a custom built vanity to include the dividing wall (IE the back of the vanity) with a mirror doored wall cabinet and the basins rather than adding a separate wall

I should have mentioned that the Nib wall beside the toilet would be full height either solid or just by adding timber slats which is my preference or glass, etched or opaque above the existing Nib wall

Something like this with smaller slats, the vanity can be made to fit your new hand basins