changing headlight bulbs - Citroen Relay

I have a Citroen Relay van and both headlights have blown on it. I bought two new bulbs today, but cannot figure out how to change them. The handbook is useless, the diagrams don't relate to this van at all, but I've found that already with the fuse box.

I have changed bulbs on other vehicles, a bit fiddly sometimes, but not difficult, but I cannot get the back of the lights off in this van to take the bulbs out, so I'm guessing I'm going to have go in through the front of the lights? Has anybody else managed to change bulbs on a Relay, or Peugeot Boxer, which is the same chassis, so probably the same set up.