Oh that looks the same flooring as we had in our hall! Still got some pieces we repurposed into a kitchen worktop for our camper. Solid wood but they had a varnish coating of some sort on which took ages to sand off 😢 They were down in our 30's house and thick but not original. Sorry don't know the name though ☹️

Thanks for the replies. @Ellie I think my partner got the idea of a horizontal one from a one pitch roof photo on here. they do look really nice. @oneplan that's a really good point re lining up windows if they are horizontal. Although I think long horizontal ones is the builders last choice as he says they'll take longer to install. We're paying a day rate so trying to get everything pinned down in advance and as slick as possible. Our internal layout is slightly different to the floor plan I added to the comments. The kitchen is going in the centre in the 'old' extension (front of the house is Victorian and existing extension is 1990s). The new extension will have the sitting area on the left and the dining area on the right (so the opposite of the floor plan). This is because the wood burner will need to go on the left side and we want the seating area around that. Do you have any thoughts on narrow vehicle windows one on either side for the gable roof? I'll try to find the photo of what I mean. Thanks

I have to completely agree with BlushingPixie It really looks like a floor (possibly pine or something similar) that was stripped or in the middle of being refinished. They may have just placed the chair there after cleaning up for the day. Either way, whatever it is it doesn't seem to have a finish on it yet. If there is they seem to be going for a more natural look. It doesn't seem to have a high gloss or wax type finish (IMHO). Possibly a matte finish at the most if there even is a finish on it at all. Best of luck to you!!

I think you could aim for the same colour LVT as your worktops. An oak coloured floor would join up nicely to grey carpet.