Everything is possible in building. If it is wrong it can be taken down and done again. As I said the structural loadbearing is done by the inner skin blockwork. The outer brick skin is weatherproofing and adds stability. The gable could be cut out in sections, especially as the window lintel can be easily propped in the opening. Whether this causes a delay who knows! Probably, knowing how bad housebuilders operate, but in the end you will want and need it done properly and carefully.
You can't tint dark bricks lighter. You can only paint them. Any warranty offered on tinting will safely expire long after Bellway's responsibilities end.
Just another thing you should be worrying about.
An "end March" legal completion does not leave a lot of time to actually finish your home.
That's under 7 weeks. 35 weekday working days to be precise.
Works remaining:
First fixing: plumbing - 1 day, electrical - 1 day and carpenter including fitting windows and staircase - 2 days
Plasterboarding:- Tack ceilings - 1 day Stud partitions 1 day, dryline walls - 3 days, jointing - 3 days.
Second fixing: Plumbing - 4 days, electrical 2 days carpenter - 4 days, Kitchen - 2 days
Wall Tiling - 2 days, Painting and decoration - 7 days
Finals all trades - 2 days, Cleaning 1 day, silicone and site snagging - 3 days
and whilst all this goes on inside, paths, driveway, fencing, turf and landscaping, electric, gas and water connections and meters.
The days above add up to 35 days! Some trades can overlap which may bring it down to 28 days but that really is the absolute minimum required to finish building your home. It also assumes that each trade will be available and turns up on site as soon as their work is ready. No doubt Bellway are also building several other homes with similar completion dates.
That is not to say it cannot be done quicker. You could double up on the trades and work nights and weekends, but do you really want a "Challenge Anneka" - "DIY SOS" home?
Quite why there is the rush I don't know. The Bellway financial year end is 31 July!
It is always better to under promise and over deliver, but all the housebuilders don't know anything about good customer relations.