Have a read of this, DebsyDoo. Having done this on a similar Zafira B it's up through wheel arch access panel as suggested. Tip: Peer into front of headlight lens before dismantling and note orientation of bulb when correctly sat in its holder. Two springy (sort of) plastic clips hold wheel arch access panel in place. You will need a torch or a sunny day. Once...
Dunno - don't do cars (fortunately OH does), but I often wonder why I have to carry spare bulbs in the car when my Renault needs the front bumper removing before a bulb can be changed. I can really see myself doing that at the roadside, can't you?