Been there quite a few times .It's best if you try finding it in daylight first.Exit on Chemin de Boeuf, under the bridge ,join the main road via the slip road(looking left) continue for about 2 km toun right and follow the logical route or the track with the most tyre marks.I think you may need your general admission ticket with you to get into the carpark!But not sure on that.Rex L.