It can be just easier and quicker and just better to just whip off the bumper, detach the grille and then separate the surround.
Bumper removal is not that hard , same with grille removal etc.
What a lot of chaps do is to source another S-line grille, which can be purchased for silly cheap money, then remove the surround, prep and paint it , then either refit on the grille it was fitted and swap with the one the car.
It saves a lot of hassle, basically just a swap over and you have a spare gille for emergencies.
Ultimately down to what finish you want and the longevity of the finish given the hammering from the elements it will get on the front of the car.