At the bottom of our Europe story, I've done up a little segment on cycling to and from Heathrow, or at least travelling with your bicycles to and from Heathrow. There are several options ... Rowan and I have used a couple of the options, but the last time we were there, we learned about more, and I've included all the options we know about here:

http://www.machka.net/RTW_2012/RTW_Europe_Main_2012.htm