Overrun,
there is no official list of category C airports.
Each operator maintains its own list.
Further, classifying an airport in category B or in category C will depends on the limitations of the aircraft type operated.
I understand that some airports could be considered B for turboprops and C for heavy jets (eg LFKJ Ajaccio).
If you are willing to maintain a list of european airports that are candidates for inclusion in category C, you can also include:
BGBW Narsarsuaq, Greenland
BIAR Akureyri, Iceland
ENTC Tromso, Norway
LOWK Klagenfurt, Austria
LRBC Bacau, Romania
LYTV Tivat, Serbia