Hi Louise, your photo didn't attach, so it would be great if you could re-upload!

I think it will look great to open up the kitchen and conservatory areas because the area is quite small. However, here are a few things to consider (this is from someone who lives in a house with a similar layout to your existing ground floor). The conservatory faces south and presumably overlooks the garden. Is this an area you are going to want to sit in because it will be beautiful and tranquil? If so, it would be better to keep the dining room in the centre area because you don't need a view when eating (except of the food). Then use the conservatory as a small sitting room. It looks like you have not drawn the plans to scale. The new hallway looks narrow and the new wall will take up space. Make sure if a new wall is put in that you will have enough space for a useable room plus a hallway. Why do you want to access the new downstairs bedroom/study from the living room? Wouldn't it be better to access it from the hallway at the bottom of the stairs. Good ideas though.

I think vertical blinds may spoil the look. How about Roman blinds mounted on the outside of the recess. This would add a softness but also get rid of the echoey feel. The other option is curtains at the patio doors and a matching blind at the main window. I would look for a fabric that contains a flash of the green you've used on the walls to carry it on as an accent colour. Then perhaps add some green accessories to help it all tie in together. It looks great so far, hope that helps. Good luck!

Photos would be helpful