The Hatton Cross area is the most popular and troublefree. Landings are close. Takeoffs from the other end - 09R - bringing them overhead on liftoff - not so good for the small stuff, but the heavies are fairly close and a telephoto will fill the frame.
But it's no good if the takeoffs are from the Hatton Cross point - 27L. This means landing is on 27R which is quite a walk from Hatton Cross, and on the airport property. I've often seen groups of photographers in the vicinity of 27R for landings and I've seen a police vehicle stopped and giving a group some attention once. But for most of the time they appear to be left alone, for a while at least. One would think that having keen photographers about would be welcomed by the police as a deterrent to undesirables.
The runway schedule on the plane-mad site is obviously only a guide. They can and do switch as required - wind changes etc. For some reason there are never any takeoffs on 09L.
If you're mostly interested in the big stuff - and who isn't - then be prepared for some boredom. In my 2 months residing in the Renaissance hotel with a runway view I did a poll and saw that 7 out of 10 flights are the small Airbuses. zzzzzzzzzzzz.