How the hell do you change the number plate bulb really struggling to get it out

Flat headed screw driver and a lot of force to pop it up and out. Might need to use two flat heads to attack from both sides.

The spring clip is in the middle of the lamp, on the boot lid edge. It is worth while sticking a bit of masking or insulating tape on the bumper before you start, in order to protect the paintwork.

Regards.