How wet does it get? What colours do you like? Will children be using it? What is your budget?

there is not a big difference between the worktop ( it is more shiny) and tiles for walls you have chosen. About the concrete effect, the finishing is matt , so it is not that much shiny but the advantage is not slippery, I think you have done good choice unless you choose your walls tiles matt also ( to me better choice) make sure your silicone is colorless otherwise it will stand out really bad when it is finished.

Many thanks for your comments but not not quite. I am new to stone effect porcelain so I am not describing it well. I found yesterday that it is known to bookmatch marble slabs to create an amazing marble mural and that there is a porcelain marble effect equivalent for example https://www.porcelain-tiles.co.uk/range/bookmatched/. It looks amazing but there is still a replicating pattern because it is "bookmatching". I am wondering if an artist / manufacturer has taken this a step further and created a large mural image requiring a large number of tiles to replicate a whole slice through a mountain of marble ... so the marble mural would be continuous not broken by the tiles and 100 tiles would be unique. And my question initially was about stone rather than marble so that the uniqueness is subtle .. but marble would be nice too.

Those painted floors look really good, don't they. She did an update on one of the floors she painted a couple of years ago and it still looked really good. Think it's at least worth a try. It's not a huge space, and if you're planning to change the floors one day anyway, it doesn't matter that much if it starts peeling after a while. Love the wallpaper :-) Deserves a floor that looks good with it.