If you've come through COA at FL300 or above its probably quicker to continue on to the UK and land expeditously rather than do a 180 and try to weave your way down through the traffic over Belgium. In that situation I would almost certainly elect to continue to a UK airport as we'd need about 90 miles to lose the height anyway. By all means show a sense of urgency, but there's no point rushing things and creating another 150 casualties.