Looks pretty good to me! It's a tight space so there's not a lot of options. The toilet roll holder can go on the end panel of the vanity cabinet, that's no problem.....or if you use a wall rather than glass shower screen for the shower, it can go on that wall. In saying that, I would use a glass shower screen to keep the space feeling as open as possible. Possibly a 1/2 height wall with a glass panel above (which would also give you a bit of a shelf for shampoo etc). All the best :)

Too dangerous with normal tub , the best way to do this is too build the bath in a normal rectangle shape and height with concrete, make the side of the bath facing the room approx 8- 10 inches or wider if space allows so that you can sit on it to get in and out of the bath, then cover with small plain mosaic tiles including the walls, You can have a shower screen or a good old fashioned curtain or nothing as long as you have the drains in place. They do baths like these in Asia and safely have the shower over the bath no slipping., they look and are special too. Safe for everyone to use, perhaps not the elderly who should only use separate showers with a stool etc. cheers,

a separate wiw and ens will give the best use of the space with maximum storage wall to disguise the volume of your clothes in chests of drawers under hanging space below high shelves and there's space in the ensuite for a generous double shower, vanity and wall cabinets but the bath will have to go elsewhere if you want to be able to stand and dress in the wiw or ens and keep the rooms feeling comfortable for two people to use together twin highlight windows will provide light and ventilation and hinged doors allow for clothes racks and/or hooks on the back of the doors

we had a custom sized shower bath built by installing a low wall, then waterproofed and tiled all around ..yours could have a glass screen and hinged door made to suit the new height ...bath depth of only 30-40 is plenty to sit down in and still low enough to step over and a handheld shower would be ideal for kids but i have to say that my very small grandchildren went from laundry tub to baby bath on the floor of the adult shower to happily using an adult shower from a very young age and i wonder if by the time your organise the new shower bath the children will be so much older and maybe you don't need the expense but a tiler should be able to provide a quote and /or refer you to tradespeople and materials needed to do the job ... hopefully it can be done without changing the existing floor tiles and maybe the existing glass screens could be recut (or just installed taller) to suit the new space and you only need a new door