HI i have just changed the driver side head lamp bulb.  
to do this i had to remove the grille - very easy 2 clips on the top edge.
This reveals 2 screws on the inner side.  undo both of these screws and a third on on the top of the headlamp on the top edge of the wing, under where the bonnet would normally close .
The headlamp can now be withdrawn.
Remove the cover at the rear of headlamp.  replace lamp.  re-install headlamp, ensuring the locating lug on the outedge is in position.  re-install screws and the grille. 
the whole job took no more than 10 minutes.
                
 Simon
                
 March 2008