If you use a heli-coil kit a suggestion is remove valve cover to make sure neither valve is open , Pack some grease onto heli-coil tool and make sure that it goes straight into cylinder to catch aluminum chips I also would make sure that piston is at Bottom Dead Center and if not 100% sure remove rocker arm assembly and use a screw driver into spark plug hole to make sure piston is at the bottom. KD Tools still makes the tool kits and inserts 14MM X 1/2 inch . A lot of time a 14MM spark plug chaser will work unless sparkplug blew out with metal on it
It is also good practice to use a "never seize" lube on spark plug threads to prevent steel plugs from sticking to the aluminum/magnesium threads in the VW heads. I have done this for nearly 1000 tuneups across all kinds of engines and never had a spark plug pull out any threads.