I see that BAA are suspending all flights out of Heathrow and Stansted.
(Looks out of window)
Is that just overcast, or is it volcanic dust?
Looking at the map, they appear to be following the precautionary principle, so we probably don't actually have dust over us right now, not down here, but they don't want to send planes up into something that might cause severe damage to turbojets. (Not since the scary time a 747 lost all 4 engines and nearly came down as a result.)
ETA: following crazyscot's link will bring you to this page of graphics file links, of which shows the latest forecast.
ETA: farewell, Denmark. They're closing their airspace at 1600Z.