Great advice dts builders! Another way to minimise visible grout discolouration is to use rectified tiles to minimise the width of the grout join in the first place. Using larger format tiles will again reduce the amount of grout needed, and where your design allows, use a dark colour grout to restrict the amount of dirt and grime that is visible.

All the joinery and floor finishes are brand new - the old ones were not in the best condition, and the layout was not working well, so it had to go!

You would have to ask SCA. I believe the gable roofs are for council (streets-cape). The cladding being corrugated, cost (pre-finished) and proximity to the coast (durability).

Pictures will only be inspiration, you’ll really need to try a sample on your floor. I’m with you on disliking redness in the floor. Can you sand back a section in a wardrobe or similar and try with a clear Matt finish and also with a white wash or similar?