la ferme des aulnes nampont saint martin

hi l wonder if anyone could advise me. Our ferry is running an hour late so we dont expect to dock in calais til.18.15 and as its our first trip abroad l have tried emailing this campsite to explain that we will be late but as yet had no email back. lm really worried that we wont arrive til late and be turned away. Does anyone know what the latest you can arrive. Thanks Sue