Hi I had the same dilemma with the dining part of my kitchen. I love the brick wall effect so decided to try a wallpaper as it's only a small wall. I'm really pleased with the results. It cost me just £9 for one roll from B & Q. You can only tell it's wallpaper by getting up close and touching it - before and after photos attached.

Bricks are a fired clay product and will give you 4 hours fire resistance so do not worry about fire. If the wall is internal then no problem re heat insulation, however if the wall is an external wall then the insulation to a new wall should meet the current heat insulation standards for a dwelling.How you meet the requirements will depend on the construction. If a new structure it should have been checked by the Building Inspector. If an existing wall then check out the construction to assess where and how it can be insulated - cavity fill would be most discrete if you wish to avoid heat loss. Traditionally almost any paint can be used but will need regular freshening . if you like the bricks then simply seal them with a proprietary brick sealant and no more painting of that wall.

That explains the “rustic” finish. If it were a full height wall it could look really good, but as it’s such a small area it just looks untidy. I’m not sure re-pointing will make much difference as the bricks are different sizes and rather higgledy piggledy in layout. I think plastering will be a huge improvement.

Way late to this thread so probably too late, but want to add if that's an external wall then please don't seal it. Looks like an old property with lime. Needs to stay breathable. If you steal it any moisture can't escape and you'll create damp problems. Perhaps whitewash with lime then add a breathable clay paint?