Thanks for the comments guys. I'm very lucky with areas around my drive that are shaded throughout the day. I move the car from one place to another when its hot and can usually find a good bit of shade for polishing.
Lower grille is fixed in by 2 screw attached to the upper section at either side of the bottom of the numberplate. Remove the 2 screws and then just pull it away.
I didn't clean the rad as to do it properley would have meant using a presure washer and I didn't want to wet everything again having washed the car yesterday. I use carplan back to black for the grille and other black plastic, it leaves no residue and can be applied with a brush or a rag.