I don't believe there will be much difference in price between a glass splash back and stone. I believe the white metro tiles and grey grout (repeating the grout to the floor tiles) will work very well, and my preference would be a matt finish. Kitchen accessories and the oak shelf will avoid it looking too bland. Alternatively, you could opt to make a bold statement by using some of the wacky tile designs that are out there, but then I would suggest considering using a white shelf opposed to oak so the tiles take centre stage.

The 2 windows are they same or being replaced by patio doors to garden? If so, which is a door? If not doors, I'd want the windows to be the same for cohesion in the space. Maybe a layout like this, banquet bench type dining area could maybe work?

Thanks so much for replying! Our architect actually did sort of draw up that as an option but I’m not sure I want to obstruct the window onto the street and lose that light source. The section near the sliding doors into the garden will have skylights as it’ll be a 2.5m x 5m extension. Will that be too dark? Thinking it’ll be ok for dinner parties. We do have a separate living room and piano doesn’t have to stay, the only reason I put it in originally is that it fits perfectly in the alcove on the first plan. He said he didn’t put the dining space in that middle bit because it would be quite dark and it’s only 2.5m wide so actually a bit tight for a dining space I thought.

Ok, thanks for the measurements (i wasn't that far off), here's the reviewed first floorplan i posted: Top left a bench (extra storage, instead of the chairs), then 60 low oven unit, 80cm drawers with hob, 60 DW, 60 sink, 60 drawers, 60 FF, boiler. Turn the old units into an island with 2x90cm units on the other side (some brands have 45cm depth units these days, extra drawers is always nice) and a breakfast bar on the side (overhang at least 30cm). Would advise against the pantry against that wall, but hey if it works for you go ahead. Depths: 65cm worktop, 120 aisle, 105cm island, leaves 120 between island and wall.