I'm very near where you are and I see these planes too. It's quite spectacular when a BA 747 turns sharply at low altitude with a roar of its engines. Most of them are in a holding stack before landing at LHR.

If you want to see where these planes are going, use one of the following web sites for live information about the aircraft's route, both of which also have smartphone apps:

http://planefinder.net

http://www.flightradar24.com