I think I'd leave the flashes off, since a UK isn't Scottish, so it doesn't need to have the flashes. I'd also be more tempted to team a black survival with black kilt hose (or just black knee socks - don't even have to have a turnover or be as thick as kilt hose - the important thing is that they come to the knee, that's all). Off-white is a bit too much of a contrast for the black survival. Maybe a gray or brown shirt to go along with it. Talk it over with your wife, with respect to the shirt combination.
-J