Insurance?…suggest that the first thing they check is their insurance, before the said six groupies arrive at airfield to re-validate themselves ‘on the quiet’… and then OMG! something goes slightly wrong…… We have all read about it i’m sure.
An instructor for a morning would be the best bet, surely? Perhaps the instructor may like to ‘borrow’ the aircraft for a day in consideration of his/her time?

Try the PFA for an instructor, there should be local ‘Strut’ (group) near you. http://www.pfa.org.uk/clubroom/struts/struts_listing.asp