Okay, appreciate the advice given so far. Went to the local tile shop with medium grey and sand grout samples and found that sand was a different shade to the sample in the shop. After taking newer samples out it looks to be my tiler samples had discoloured. So in the end sand was much browner than I wanted. Below is medium grey and also a lighter version (manhattan). Also size of the job. Now wondering if I should go lighter?

Hi Lucy, For a toilet floor a darker grey grout would be best to hide any stains or spills. However from your photo the base colour of the tile looks quite beige, so a coloured grout like the BAL Micromax2 in Lime would be a good option, this will keep a heritage look whilst being more practical than an off-white. If you'd like to test a few options, we offer grout sticks in our stores which you can take home and lay next to the tile in the actual light of your bathroom to help you decide and make sure it's a good match before purchasing.

I think it all depends on the look that you are going for - with these tiles, I too would be tempted to colour match as closely as you could, however it also depends on the style and wider context of the house. I have a Victorian house and old battered boards in our living room - they have gaps between the boards which effectively almost look black. When we did wood effect tiles in our en-suite, I bought similar coloured tiles and then used a dark anthracite grout to get the same effect as the living room. However the tiles you have chosen are a different style - they’re a lovely fresh contemporary wood effect compared to my old battered boards, so a more neutral colour that blends in would look fab!

I decided to do what your thinking about (coloured grout on floor, then white grout on walls). I think it looks OK not odd, but obviously is personal opinion. Pic attached part way through work, I didn't use a grey marble but a gold vein marble. I think I would have preferred tiles lined up between floor and wall still but you don't notice too much after a bit. Gives you an idea on effect