No to the grey - your wall seems to have a green tinge in them, so I would say either green/grey or a warm white tile with darker grout. If you choose the right grey/green, it is a classic look so shouldn't date. If you are a bit scared to choose colours, why don't you get a couple of warm white sample tiles and put where the splash back will go. You will soon see if it looks too stark....(maybe another idea, but possibly not a good one - why don't you see if you can put a few pages from a blank sketchbook in the whole area where the splash back will go (not super white white, but a warm white). That could also possibly highlight how stark (or not), the white may look. I can see what design tank is saying, as your cupboards appear to be more cream than white in the photos and if this is the case, then I agree the white will most likely look too stark. My cupboards in kitchen were white (but a warm white not a cool white). The stone bench tops also have the little speckles of stone in them..I can't remember the colour Ocean foam/Osprey.......but even with those colours and them not being cool whites, I thought the white tiles looked too stark against them. I therefore went for a glass splash back and ever since I then went to think of designs for my bathroom renovation, I constantly regret going with the glass in the kitchen and modernising the house too much..........definitely don't do glass if you are wanting to keep a classic charm to the house. In a long winded way, I think yes, I also think you should just stick with the grey/green. It will make a statement. Not the right shade...but another example....it may be hard getting the colour of the tile exactly right given that the walls are already painted and the tiles need to match.

Thank you everyone, your thoughtful advice was very welcome. I'm attaching a photo as its all finished. I selected Olive Reserve for the splash back and painted the wall above it the same colour. As its a big room with lots of light and a large window it doesn't dominate. The glass is so easy to keep clean and I love the way it reflects the garden and light. Have to say though some people are stunned into silence when they see it, but as the cupboards and bench tops are quite bland I knew something bright was needed

Oh, forgot to add...........If you painted / wallpapered then put clear glass on top, if adhered/glued, there is no guarantee the glass will come off in one piece. However I have a friend who wallpapered, then put clear glass that was fixed on the corners with bolts (can't think of the word), so that it was removable. You can probably get a tiled look paper. Each to their own. I'd stick with a painted glass splashback.

Thanks for the input! do you think that subway or 6x6 tiles would be better in the shower? Im not sure why but i was thinking that the 6x6 might be more consistent with the style of the basin. Dark blue or light blue for the accent tile in niche? Its a VERY small bathroom which was why I was leaning towards white floor. Trying to make it feel bigger. But maybe thats an error. This is the floor tile that I was considering. Too busy? I have to admit I like the dark blue tile of the last photo that Dreamer posted alot but was worried that a dark color would not work in a small space.