My GF's house mate managed to reverse into my O/S rear quarter

He must have been smoking meth to have bumped me given the circumstances, but, it happened, and now there is a nasty dent and scratches just beneath the filler cap and some on the bumper.
Pics to follow.....
But, basically, he is happy to pay for it rather than claiming, now this panel obviously isn't removable, but is it double skinned? Anyone and experience in this sort of repair?
