Timber with timber can work brilliantly, and it's in keeping with the mid century style you want for your home. This room (below) is a little similar to yours, albeit with less of a pitch to the roof - the large feature lighting helps to break up the expanse of timber on the ceiling. You have a lovely open plan area, so I'd be inclined to use rugs to create zones and a cosy feel. Rugs reduce the impact of a large expanse of flooring material. They have the benefit that you can swap things around to change the look and layout at little cost. I think one trick may be to define your "walls" carefully, and paint these before you go with a new floor. This should give you a sense of whether the timber is overwhelming, and how to balance it. E.g. You might decide it works best to paint the kitchen cupboards to white, to give you a more seamless look and work with your new counter tops. If you want to experiment with the "paint ceiling" approach - gulp, it's a big one!! - then maybe that small section above the kitchen bench, at a different angle to the rest of the roof, could be the spot. It seems to have the same horizontal line as the wall, so even if you don't like the painted look for the whole, you might be able to get away with blending this into the walls. Best of luck!

Sorry, I just realised the photos aren't the best...the house colour is Dulux butterscotch & the trim is heritage red/manor red

Looks fabulous.

siriuskey thanks for your input. I think I will keep as you suggest. However in the hallway I will do a transition so the boards run the length of the hallway, I don't think I can live with them on the diagonal there as it will make the hallway seem smaller. Also the door to the hallway is closed majority of the time. Thanks Kate for the photos, I can better visualize the boards now as per the drawings. Appreciate everyone's advice, I think sometimes (perhaps all the time) I just overthink things. This renovation is not a small undertaking in cost and I want it right. This is our forever home and I have been dreaming of this kitchen for years. Due to COVID lockdowns and long lead times on things at the moment I have had to rely a lot on buying online. This has been the hardest part as I am a touch and feel type of person. Thankfully I have had these floors before in our previous house so that was one less stress.