I really like your wallpaper idea. You could use a floral or a green/grey base with some large foliage to really brighten it. An upholstered or rattan chair would give the space room to breathe. You could put bookshelves up on one wall or both if you wanted a reading nook. You will also need a floorlamp behind the chair. If you didn't like the chair idea then low level open shelving below the windowsill is an efficient use of space. I would consider some plants on the windowsill to hide the view of the driveway. You could also do the opposite and have window film at the bottom for privacy whilst still letting the light in from the top half. You could also paint the window wall a different shade.

Hi Gill! We agree with Isla, the wallpapering idea would add a nice decorative touch whilst brightening up your home. In terms of the curtains, we would suggest something minimal if you were to add a wallpaper frame. I hope this helps, Sarah! 😊