Having given this some thought, and a quick rummage through the web, your
best bet is probably to have a word with the Silverstone race circuit. From
what I can see, they don't have their own on-site station, but seem to get
their data from Birmingham Airport. I know they have a station set up on
race days, but I'm not sure if its there and working all the time. It may
well be, recording conditions privately, only making them publicly available
during the big occasions.

You've also got Kidlington Airfield about 15 miles south of you, which
should be recording full time, and there's probably something up at
Towcester Race Course too.

jim, Northampton