I think you can do it with the bumper on. I'll have to look it all up. From memory, the centre grille ones out, then you reach behind to release the clips.
But ont panic about removing the bumper. It's an easy job. I allowed a day to do it when I worked on the headlights, but the whole thing was off in 10 minutes. You may only have to do the top and drop it forwards.
Three screws in each wheel arch. Pull the sides out from under the headlamps and wings. Undo the fastenings across the top, and it falls forwards. To get the whole thing off, you undo the four or five screws under the front edge.
