I think you can get freestanding ones that look like sideboards and hinge open on the longer edge. Alrernatively, you could get a daybed that extends out to a twin.

Paint them all Hague Blue. I don’t get the whole painting a feature wall thing - the walls and colour are not the feature, they’re just a backdrop to everything else in the room. Our north facing bedroom is Hague Blue and still feels bright and airy despite the lack of direct sun - white bedding, light flooring and bright accessories

Hi, To design your TV and feature wall, consider extending wood panels or slats across both the main wall and the alcove for a cohesive look, with the TV centred on the main wall and a darker panel backdrop to help it blend in when not in use. Alternatively, you could make the alcove the focal point with wood slats or panels and keep the TV wall simple with a complementary dark colour. Another option is to treat both areas separately—using slats on the TV wall and a contrasting treatment, like paint or wallpaper, for the alcove. Incorporating the old chimney niche with decorative elements or lighting could also enhance the design. Thanks!

If you must, only one wall. If doing two walls you should do all four walls. Two walls doesn't make sense and just looks like a half-done job. To make it a proper feature rather than a randomly wallpapered wall, it should be the wall behind the bed, so I'd finalise the bed position and then do the appropriate wall. If you do the 3m wall and keep the bed on the 4m wall, it'll look like you wallpapered and then realised the bed was better on the other wall i.e. it will look wrong - unless that wall then becomes a different purpose which makes sense (like aforementioned study for example).