Tell the truth!
Been through OASC Pilot selection myself, got accepted. Just say yes you have tried it once but you condone its use etc.. no place for it in the military etc.. they aren't really all that bothered. Pay more attention to knowing everything about your own life (ie be able to answer their questions without hesitiation) and know lots about the RAF (eg they asked me what is special about the Merlin.... 3 engines, inflight refueling, full glass display). oh and show some physical courage in the hangar exercises, dont give up, be the first to volunteer to jump etc..