Here’s a screenshot (click to enlarge) taken at 12.15 p.m. (British Summer Time) today of flightradar24.com, which shows live aircraft traffic over Europe. The single plane in British airspace (over the Isle of Man) was a flight from Vancouver operated by Thomas Cook, destined for Glasgow but redirected to Manchester. The Professional Pilots Rumour Network has ceaseless commentary from its members about what is and isn’t going on.
http://www.lrb.co.uk/blog/2010/04/16/inigo-thomas/planespotting/If the site loads (it's very busy), it shows even less outside Italy now. However, Scotland has recently been opened up - though whether that'll last, I don't know.