I've just found this link to a booklet that Manchester airport has produced for those travelling through the airport with ASD. It's a sort of social story and could be helpful to lots of families. Could be helpful for those using other airports too.
www.manchesterairport.co.uk/manweb.nsf/alldocs/4D4CC20F97DD74008025736400407C2E/$File/Airport+Awareness+book.pdf