Right First off if you have a 1.2 or 1.4 you "should" be able to do this from above with a bit of care.. if you have a 1.9 have "fun"

The Bulb in question is a H1 55 Watt

on the 1.2 you can fit a small family in the void however having seen the 1.9 you might be able to fit a hamster........

if you have a 1.9 your best bet would be to jack and axle stand the car and remove the wheel and arch liner (unless "T" has stolen your under tray)
this (the arch liner) is held in be several screw and plastic "nuts"

right assuming you have now managed to get to the back of the lamp

you need to remove the cover (Lee Punto says he needed a rubber strap wrench to open his however i have never had a problem)

this removes with a small turn Anti clockwise.. (about 1/8th of a turn)


at this point dont pull the cover too hard as it is still connected by wire to the bulb you are about to replace and you don't really want to damage the connector