I'm not a fan of shower over bath either but agree sometimes for some people it's the best solution. The makeover is beautiful. Two things, just in my opinion. I always wish for a grab rail when using a shower over a bath, as I sometimes do in hotels. I felt that way even when younger and more agile. Surely there could be a way of installing something to hold onto when stepping in and out without it looking like a nursing home? I suppose in a bathroom such as that shown I would hold onto the towel rail. I've always wondered about vessel basins that slope inwards, is it a problem for cleaning behind them?

Hi, unless you take a bath at least once a week I'd skip the tub. I'd rather enjoy a bigger walk in shower, which is also a lot safer than climbing into a tub to shower. If you have the space instead of a tub and shower I'd consider a double vanity to give you extra storage space. It's a little luxury you will come to enjoy when everyone is getting ready on the morning.

@bigreader i'm not a fan of built in or back to wall baths. Functionally i get why they are used but i just don't like the look of them. 
 @Ken Evers Thanks this is what i'm after some practical experience with people who have lived with this setup. As it seems to be a mixed bag, people who has said yes it's an issue but are guessing having no lived in this setup and some people who have lived with it and said not a big issue, but sometimes they are defending their choices lol. The existing bath has a drain that sits close to the wall at the same end as the shower due to the curve of the new bath this could be utilized as it would not be blocked but it would be hidden the idea was to use this as an additional drainage point with no additional plumbing. between the shower / bath section and the rest of the bathroom there will be a floor to ceiling screen approx 1000mm in length, where the current shower is that waste will also be used in addition as this will sit neatly under the floating vanity that's going in. In regards to the tiler i have used him previously and was very happy with his work, that said outside of waterproofing your right, How the water flows is a quick way to kill a good looking bathroom. The biggest concern i had was on the far side of the bath between the wall and long side. So for example against that wall? Idea is to have it slightly raise as per this photo gradient for a lineal drain. A small waste is already in this location so it was going to be used for additional drainage with something like this which is sitting under the floating vanity and in the gap between bath and wall. @Kate Yep there is some compromise we are just trying to determine how much of an issue this is for people who have actually had this layout?

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