Our side entrance is bordered by a brick wall, and we'd like to cover the bit between the house and this wall. The other side of the wall is pavement - the road I live in - which we're sideways onto, so the pavement runs parallel to our house. if you get my drift. The wall is flat on the outside [pavement side] topped off with concrete coping stones. The run of the path [inside] is about a 12 foot [3.65m] and 5' 9" [1.75m] approx wide.
 the side wall has pillars, I'm guessing it's best to pack these out, so that there's a flush run?
 looking to collect any rain water that falls on it, so is the easiest way forward to build a sort of gully/ u shaped bit along the side wall and sit the guttering in that?
 what sort of fall from [a] the house wall to the side wall should I be aiming at and [b] on the guttering?
 we'd like to keep it light and airy so corrugated plastic or twinwall? I'm hoping this is reasonably clear!