If you are going to the effort of retiling the fireplace surround, would you consider going to a bit more effort and creating a full wall unit which incorporates the fireplace and the TV, with extra shelves and cupboards to display and store? (I also have reservations about the heat and the TV and associated wiring.) This may also address the lack of symmetry associated with the location of the fireplace, if that is a consideration. Do you use the fireplace often enough to justify keeping it? Alternatively, a wall unit on the left hand wall, which is where the power and TV points seem to be, may be the best solution - as previously suggested. All the best.

A nice whitewash wall/paint treatment would brighten it up if done in a light color. Or I would paint it but not sure if all the knots will bleed through? If so then I would use an oil base Kilz to stop bleed through and paint it depending on the interior design I want for each room. I would not paint the ceiling for a more Montana look,

The freestanding bath fillers are vulnerable to being knocked. When you think about the physics of it, it is asking a lot of a small fixture to resist that amount of leverage. Talk to your architect. They should be able to come up with a support that fits with your design and is a bit more robust than the long and thin proprietary bath fillers. Also how far is your bath from the wall? If it is closer than 300mm I would still be waterproofing the wall, and with young children around I would waterproof it even if further away.

@Enoka Seneviratne