I need a good, reputable window company that can install anthracite grey windows: upvc or aluminium but provide an alternative modern porch for our arched porchway.

Sliding doors are proving very popular at the moment as they can stack to one side and not protrude into the garden space and be easier to move than full set of bi-folds so that would an approximate opening of about 4m with 3 x 1.250m (plus frame ) panel of glass that would all stack in parallel inline. Or you could try panoramic doors they are more versatile as they are detachable from each other and give you more options for you layout at the finish. There a tutorial on you tube ? Do you have building control on these works as I am finding that architects are making us use a lot more steel as in a goal post design for stability, depending on how wide you want to go with the opening?

I think it would be best to look at porcelain tiles for outdoors, so long as you find some with good grip. Natural stone - sandstone, limestone, granite etc would probably all look good but may get ruined if the children like painting outside as they’re porous. Even with a sealer, it may be difficult to wash off properly.

Anthracite in my opinion