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?

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!

Thanks for the interest, we decided on dark grey ('graphite') in the end and I'm happy as I think it goes well with our dark grey cupboards. We will put a pale oak shelf above to match our floor and bring some colour in with plants etc. These are the tiles if anyone is interested. I tried about 8 samples of rectangle white tiles from both high-end and high-street sources but I love these as they are a fairly strong white but with the rustic texture. https://www.toppstiles.co.uk/artisau/artisau-gloss-white-tile?gclid=EAIaIQobChMIwoekh_LN7QIVlWDmCh1OmQAPEAQYASABEgIkIPD_BwE&gclsrc=aw.ds

Yes. removing the grout would need to be done with a diamond grout removing tool and it is near on impossible to do it without chipping the tiles. Your gloss tiles will show the little chips even with white grout. I personally think it looks good and won't be so busy once the kit is in there. Id there a mirror going somewhere etc?