I currently have about 5 large boxes of books in my house and 5 “unused” alcoves so alcove shelving seems an obvious solution to me! What I’m struggling to decide is 1) How far recessed from the alcove the shelves would look best (2cm or more in an alcove that is 30cm deep?), 2) how chunky/thick (top to bottom) the shelves should be and 3) whether to pack the shelves in eg for novels without leaving much space between shelves or make a taller space on the bottom shelf for photos etc? Any ideas please?

Consider the following: Remove the existing small trellis from the wall; Paint the rendered part of the stack in a dark colour; Trellis the rendered part of the stack above the bend - make it substantial to ensure coverage; Install a tall statement pot at the base of the stack; Plant and grow jasmine up the support (choose from winter or summer flowering); Enjoy the lovely fragrance when you exit to your outdoor space and admire the pale delicate star shaped flowers.

Sounds like you've made huge steps to create a modern open feel which you love.  Why stop now just for the sake of a future buyer? If future buyer wants traditional features then it already sounds like you're wouldn't be the right house for them. Unless you're planning to sell in the next 2 years I wouldn't be thinking king about anyone else, it's your home.  But having said that each room ca  have it's own feel so if it suits to keep it I wouldn't worry that it doesn't 'fit in' with rest of house.  Basically, I'm saying be confident to do whatever you want to do! Lol.

Should I have the chimney breast removed first and then a fake one to fit the TV into it? There’s no chimney breast above so nothing to support. What are the cons of fitting the tv into the fireplace?