Phone the Bournemouth ATIS (recorded information service which among other things gives the runway in use, wind, etc) as near to your departure time as you can. It's the same recording that pilots at the airfield can pick up on a radio frequency at the airport to save the tower having to give basic information. Updated every 30 minutes. If you're not a pilot know that the update time given is given in GMT, now the clocks have gone forward for the summer this is one hour behind local time.
If they say "Runway in use Two Six" (most common) you will be heading westwards. If they say "Zero Eight" you will be going east.
Bournemouth is on 01202 364151. For others in the UK they are listed at :
http://www.metoffice.com/aviation/se...etMET_2006.pdf