I was horrified when I read both the manual and posts about replacing the Zafira headlight bulbs.
After trying all the various methods, I found that, firstly, it is darned near impossible to replace the passenger side low-beam bulb via the under-wing hatch. Forget it!
The easy way: under the bonnet, remove the plug with red locking mechanism from the front of the fuse box then remove the socket in which it fits, by sliding it vertically upwards. (Both will remain handy, on their respective wiring.)
Next remove the top of the fuse box by means of the ridiculous fastening mechanism.
You now have adequate room to get your hand to the rear cover of the light and then to the bulb holder, which is removed by turning anti-clockwise. The rest is easy and replacement the reverse of removal.
Job done.
David B, March 2017