Clinton's right. That, Ian, is a bummer.I would say go ahead and go to church. Laugh about the gig and get everybody else to laugh with you.
Way back when, my little sister, Pat, gave me a piece of advice that has stood me in good stead many times. She was a champion figure skater (U. S. Junior Ladies Champion in 1953 and seventh place in the World Championships in 1955). Even though she's five years younger than me, she was an experienced performer (as a skater) even before I started doing much performing as a singer. She said something that really stuck with me: "Always assume that you have to be about thirty percent better than you think you need to be -- because when you go to perform, nothing is ever going to be ideal. Something unexpected will always go wrong, and you will have to be able to compensate for it."
Boy, was she right! And on those rare occasions where everything does go okay -- well -- just give thanks and enjoy it. Better luck next time!
Don Firth