The brick pattern looks most unusual in your picture, is that so or is it the photo quality giving that pattern? Are the dark grey windows what you have already? How old is your house? A lot of questions but just to clarify things. Dark grey windows rarely look good with red brick so lighter windows would be a better option I feel.

I would be more tempted to change the garage doors. Is your house 80's or 90's? Rendering will need constant upkeep like cleaning if a light colour. It's also very expensive and may not be necessary. Your plants and tree are lovely. I also think a lighter front door would help, it's almost like a black hole in the pics. Look for examples of houses in your era to see what others have done until you see one you would like to copy.

Sorry but think the proposal looks odd. I would reuse your original bricks when incorporating the middle garage into your home. Are you knocking down the end garage and rebuilding or are you able to build above it?

If knocking down I'd reuse the original bricks for a plinth all the way round. If you can build above I'd clad the new build. Vertical cedar would be contemporary or hanging tiles more traditional. I like the original brick detailing and would preserve it.