I should ring them up and ask. I was going there a while ago, but didn't in the end. I rang the ops number in the AFE guide who told me it would be about £20 something plus overnight. They referred me to ATC for the PPR bit, who gave me a handling agent number. I haven't got that number any more, but I remember it wasn't any of the ones in the AFE book. Apparently this handling agent (the one whose number ATC gave me) does GA. You call them before setting out, and they do the booking in for you and collect your dosh.
Hope that helps.