PPCGB just clips to the top half of the rear bumper mate. There were two bolts which held the oem bumper below which weren't needed but the fitment is fine. Dont think theres a great deal more work in prepping the bumper in comparison to any other sort of bumper really mate, might be worth giving it the once over and making sure the surface is all good etc but that'd likely be picked up by a good bodyshop when its sprayed etc. Mines booked in and all 3 quotes were around £200 ish (probably not the cheapest especially if you have a mate who can sort you out with a better rate perhaps) for gloss white with either satin/gloss black exhaust valance.
I did notice where it met the wheel arches, one side protruded a tad further so I'm gna see if the bodyshop I take it to can work a bit of magic and tidy that up a bit but it all looks decent otherwise.