you dont need full rear quarter panels, its just the little infill plate that sits below the rear light between the bumper you need for them, theyre only cheap.

similair story with the front panel, theres just a little plate spot welded on which you can buy seperately, or just unpick them from a mk6 in the scrapper, plenty about. That supports the mk6 headlights.

but as cossiedevil has said about the filler cap being different, the mk6 hole is bigger, you would either need to cut out a section from a mk6 or buy a repair section for the mk6 filler (i know they do them for the mk5, but not sure about 6?) or the third option is to change the full o/s quarter panel for it.