You can get some good shots of aircraft at the hold for either end of the runway but you will need something to stand on.
I havent shot from 26L but the fence is pretty low so maybe a camera case would be tall enough to stand on if not small steps. The ground dips down right by the fence so shooting through the fence would be too low I would guess. Im not too sure on how the police would take this as there is always a heavy police presence around this area.
Shooting from 08R is pretty much the same. You will need a good size pair of steps to take shots here, minimum would be 5 foot I guess to clear the perimeter fence, anything lower than this and you get the hedge in the shot too. There is also a crash gate which has a couple of handy holes in it which looks right up the taxyway. Depending on what aircraft and how many other people are there this works out okay. If its a Cityflyer RJ then you will have no problem taking a shot but anything interesting and your have to take turns with everyone else to shoot through the holes
If you get there early 6.00am then normally there is nobody around apart from me!!
Hope this helps, have a look at my recent shots to see what itslike for the 08R end.