You need to remove the complete headlamp unit, I've done this myself before. Loosen mountings and clips for the front bumper, pull bumper forward just enough as to loosen headlamp and pull out. Once you have the whole headlamp unit out undo all those metal clips right round and remove lense. Do NOT touch inside of lense as this is covered with special film to try prevent fog build up! Best thing to do is to try blow with compressed air. To prevent this from happening again make sure the two access covers for globes are fitted right.
Regards
Ant.