I tried and failed to unclip the whole light unit so I replaced the bulbs by doing the following:
Pry off the cover with a flat bladed tool. I made one by grinding down a hacksaw blade but I think you could use a jewellers type screwdriver or similar
Next loop some wire around the ends of the bulb reflector and carefully pull it out evenly
To aid pulling the bulb out, add some sticky tape to it (I used paper masking tape)
Pull the bulb out!