You could mount a TV which can swing out from the entry wall from the main house, or on the one opposite one near the back sliding doors, or on the floor, in the corner. Depending if you need storage on the back wall, you could have your lounge at the back of the room, or have a walkway between the back wall and the lounge. An easy moving lounge is great for moving into different positions around the room. I like the idea of the bar as a drinks trolley. Actually furniture on wheels is great for rearranging whenever you like. I usually have wheels mounted to furniture as I live on my own and it just makes it so much easier. Another idea, is a buffet across the wall of the three windows and a tele positioned placed above or on where the brick wall is in the middle of the three windows, and the buffet can act as a bar and whatever else.

I know you didn't ask for garden advice but when you've taken up some of the great suggestions to finish the room it will still look and feel unfinished because the outlook is bare. Jacinta nailed it with her final comment. Linking the room with an outdoor living space and some trees and shrubs to soften those harsh fences will make a big difference.

re the floor, what about garage matting tiles, as in photo attached, but lay them in a groovier pattern, perhaps a chevron or 60's pattern, if leaning towards MCM. It may not be any dearer than the cost after getting a tiler in, if laying tiles? Also, you can take them out to clean them if need to and change the look whenever you feel the need!

Yeah I reckon be super careful with this one....be conscious of making changes that will impact the character and balance to the facade.......when it comes to this era and style, scaling of the fenestration is really important......below is a project that we developed a new home, but the client wanted to reference the homestead type of building of similar era to yours.....that entry door with the highlight window is an important thing to keep IMO, possibly you may need to get some further architectural assistance to ensure you don't make changes that are incongruent to your beautiful property