The edge of the bumper is a few mm proud of the wing on the near side, (see pic).
Do I need to remove anything other than the headlight to loosen the fixing, and, hopefully, correct the alignment?
Mac.
The "fixing" behind the headlight is only a little plastic tab. you may also have to release the front of the arch liner to reach the screws that bolt the bumper to the wheel arch.
A2 > Audi Workshop Service and Repair Manuals > Body | General body repairs, exterior | Bumper | Front bumper | Removing and installing front bumper - exploded view
As Graham said, its just a little white plastic tab. Try giving that area a thump with the palm of your hand. There's not really much to align in that area.