Better to convert the 3.5 X 2.4 bedroom in to bathroom, your plumbing is next to it. Your study should remain where it is.

The other showers throughout we are just keeping the same tile with the niche so wanted to change this one up seeing as it's a big niche and make more of a feature of it. Am thinking a herringbone type tile or even small hexagons but it's more colour that I'm not sure about. A lot of those tiles are marble like colour The style of home is contemporary/Scandic if that's even a style ha ha!

It can either look really dramatic or too dark, depending on the size of the room as well as your other components. I've attached a couple of images of our work using dark tiles, the smaller bathroom we have surrounded the bath with dark tiles but then balance it with an extra large mirror to bounce the light around the room. The larger bathroom we have taken the floor colour way onto the wall but used a different texture on the walls for drama. Hopefully this gives you more of an idea but you shouldn't to nervous of the room being dark, it's where you can create a contrast as well as textures. Look forward to seeing what you go with in the end.

Look at what shampoo bottles you use and size accordingly. I know we have 2 pump bottles pls bath liquid and a couple of extra it,es for individual needs.