You need pop.... I do not think gray would give you enough. Maybe you could paint the door red and replace the awning with something more refined. if you could find some of the of the same or coordinating bricks from the chimney then you could make two poles out of them and a wooden roof painted white. Or for a less costly route just paint the door some vibrant color an all the trim a nice clean white. You could also get some potted plants for a little more color.

I once picked what I thought was a soft orange red for our bed room. It turned out to be Home Depot orange. As my husband refuses to paint a room more often than every 5 years, we lived with that orange. At least I was mostly there with the lights out, and it did make our north facing bedroom more cheerful. But for some reason we found ourselves at Home Depot much more often then!

If it's a concrete slab construction the plan/specification should allow for your different flooring types. For example if you're having real wooden floor boards on battens over concrete throughout then the finished height will need to align with finished height of tiles (for example) in the bathroom and laundry. The slab would be poured higher or lower in the tiled areas to achieve a level finished surface throughout. What this really means is that it's best to know & specify your flooring for each area & discuss it with your builder before construction commences. If it's all one level then it can be overcome by screeding to raise the level of tiled areas to match the height of the wooden flooring. However if your wooden flooring is direct stick, therefore finishing lower than tile you may end up with a small tile edge. In this case a metal strip is used along & under the edge of the tile at the junction to protect the edge of the tile. It is possible to have polished concrete & wood floors finishing level however you need to make decisions before commencement ie. floorboards on battens, engineered flooring, or laminated flooring, as they would all have different finishing heights.

Do you get moisture through the board lining? if so you need to look at fixing the roof from above but if you just have dust coming through than adding plasterboard between the beams would be a fast result and the labour wouldn't be expensive as the time it takes is quick and if you pay for someone to fill gaps and paint well this would take time. Ask a plaster to give you a fix quote and a the same for a painter. Again if you have any water coming through you would need to fix that first. as mentioned in the comment above I agree you can add insulation between but if you are after a quick low cost fix just plastering between the beams would be good for you.