It is indeed an excellent trip; particularly the Heathrow low level crossing.
Here are a couple of clips (first posted in the PPRuNe "Personal Flying Vidoes" thread some time ago) taken by 221B and myself from an R44 while flying the London Heli-Lanes (thanks to SteveR for hosting them):
Shots of London following the heli-lane along the Thames from East to West, Millenium Dome to the Battersea Heliport (39Mb):
London
Shots of Heathrow following the heli-lane South to North (24Mb):
Heathrow
RC