Hi, I have done this once before. I caught the tube to Hatton Cross, I then walked to the petrol station, along the A30 for about 2 minutes, then there is a small park area, with a dead end road called Myrtle Avenue (quite famous amongst Heathrow regulars!) and if runway 27L is in use for landings (check here - http://www.baa.com/assets/Internet/H...ics/Heathrow_RunwayAlternation.pdf
) So basically you want 27L to be in column B for landings on 27L during the day (they are nice and low
) to get some cool photos.
An idea of what you will see if you time it right - http://www.airliners.net/search/photo.search?album=12613