Since my UK black survival has faded somewhat (neither my original or workman have) I would lose the black hose and wear the off white, or better yet find grey hose and leave the black flashes. Black (Very Dark Grey) and off white are neutral colors so any color dress shirt is fine (actually you could match flashes to the shirt if you wanted). Another good option is a tartan shirt (I have a Black Watch dress shirt that I wear with UK's quite often).

Adam