Thank you everyone, I sincerely appreciate all your interest and advice. Since I posted last week the electrician has installed a piece of kit that allows one of the circuits of 12 spots to dim to dark. It's called a Hamilton GRID-IT LED dimmer. The same piece of kit has not worked for the other circuit of 18 spots. As instructed by my electrician I have returned the fitting to get a replacement as he thinks it may be faulty. We will try again next week. I have attached a photo of as much of the ceiling for you to see for yourselves. Jonathan, thank you so much. The ceiling is the bog standard 'Brilliant White' but the walls are Farrow and Ball 'Strong White' which is a very pale grey which has helped reduce the dazzle. I will look into toning down the ceiling too. I hadn't thought of that, so thanks again. Clever, thanks for all your interest. I can't find the technical details of the spot or the dimmer but have attached a photo of the spot. As mentioned above, only the circuit of 18 in the extension doesn't dim to dark now, but the electrician is going to try and fit a replacement dimmer next week. Thank you so much. Source, thank you, I did wonder if that is possible. I'm not sure if my budget can stretch to that but in some ways I think that would be the best solution. I will ask my very patient builder to quote. Thanks again.

I think the Graphite splashback will co-ordinate nicely with the island; my only worry, personally would be everything being white And grey as it could look cold...But this is your space and it should be how you like it as you will be spending times... As you prefer a minimalist look, I'd say large format tiles to minimise the number of grout lines. This could be in a light grey or a slightly darker grey shown in your image. To add more interest to gloss cabinets I would consider white-wash/light grey wood effect tiles...This will help add texture and slight warmth to the room. All the best.

There are a fair few crittal posts if you search. Thought these may be helpful: https://www.houzz.co.uk/discussions/crittall-internal-doors-effect-any-other-alternative-dsvw-vd~4077115 https://www.houzz.co.uk/discussions/economical-way-of-creating-crittal-style-doors-dsvw-vd~3056787

@Jon Burchfield thanks, that looks really nice! Slight issue is that we have a pitched roof on the new side infilled area. Unfortunately planning constraints mean that the height at the wall will be 2.6m falling to just 2m. I know the velux windows are recessed into the roof but if we have tall units on that side it might block out the light, how high are the units? Having a 450mm unit in that corner would be practical but I think it would look a little odd if we had 600mm units next to it. Perhaps 450mm either end with 3 600mm in the middle would look ok? @Mark Bassage @kwg kwg Thanks. Take on board the hob suggestion from everyone. Seems sensible to have it on the other side. The oven/microwave is a tricky one, if we go with the peninsula design unless we have them under the counter then the only space would be just on the left as you enter. That's practical, but we're slightly concerned this ruins the nice open feel you would get to the left as you enter. @i-architect that is something i'd considered, first impression from the company is that it would be possible but i'm not sure why. I'll check with the builders. It would make access to the under stair cupboard a little trickier but might be more practical to make the most of the kitchen space