It is very easy...

you take a flat head screwdriver and insert it on the right hand side of
the light(pulling downwards).  Once the light module is out, disconnect
the cables for the bulb.  Then insert your fingers into the rear of the
assembly, i.e. tips of fingers pointing towards thr boot, and pull two
clips to the front of the car (left and right.) This now gives you
access to the bolt for the arial mast, (think it is a 8mm bolt) unscrew
from the inside, and lift out from the outside

Rgds

Graham