The front mud guard arches have to come off, then the top bumper and you'll need a special tool or make one up to turn the bumper fixing screws ¼ of a turn:
There's a lot more to it and you may need to remove the headlamps and bonnet release cable to get to some of the fixings, and a load of trim before getting access to the inside areas to release the top part to get to the trim off.
If you're getting the bonnet fixed, I suggest you leave it to them as they should have the tools handy to do this part.