Thank you!

Think twice about tiling the whole room. I agree with your initial thoughts that the feature tile is a bit random and I don't think it works with the large format tiles. Could do the large format tiles full-height around the shower and then just to half-height (or less) around the rest of the room. Painted walls above which can add colour. Or do large format on floor and the green tiles on walls? Or a combo of the green and a not-large-format white/neutral tile on the walls? Remember a plumbing merchant's job is to sell you as much stuff as possible - in this case lots of expensive tiles which are mostly unnecessary. Find photos of bathrooms you like and examine how they've chosen tiles - how much of the walls/floor are tiled, what size tiles are they using, what pattern are they laid in, what colours are they using.

This is very helpful thank you

Definitely oak but I would look for a warmer tile other than anything greyed. Mandarin Stone Kast White is a warm white. I am currently having two bathrooms done and going through the same dilemma. I have picked the base tile first before considering an 'accent tile'. Choose warm lighting and personally I wouldn't tile up to the ceiling unless around a shower or bath. The boxing in around the toilet, I would build out a false wall that spans the length of that wall the goes behind the shower, bath and loo. If it is just the height to accommodate the cistern it could streamline the whole space.

Really like these ideas thank you

I would suggest a shade of crimson orange a lighter shade or a crimson pink still more lighter because everybody goes into the bathroom atleast twice or thrice a day and these colours might add minds silence 🤫

Oooh interesting idea thank you!