Did this yesterday swapping a front bumper!
You need a LONG 10mm extension to get those main 3 bolts per side. Made things way easier when I borrowed one!
I also found the top bolt on both sides had a 16mm nut too. don't know if this was an addition or mine being a 2005 PF 4.2 petrol model made a difference?
In my case things were not completely successful as the silver bumper was the wrong silver and only noticed once part fitted, the old one had damage and grills lost/popped due to an Ikea car park kerb where the suspension settled and dragged over, plus a few other issues!!!
Couple of Axel stands are recommended and not trying to do the whole thing in an afternoon when you get a stuck under bonnet nut because someone had rounded the star drive, the other one had a machine cap allen bolt, so i'm guessing that someone had killed that one previously.
On the upside I had two iffy parking sensors on the old bumper and that now works nicely though I lost headlight washers and I'm guessing i'll be repeating this in the future when I find the correct colour bumper.
Good and helpful thread though