I think you're going to do fine Karen!
I'm terrible at standing in front of people & talking - I often forget to breathe! LOL - but I have taught a workshop at my quilt guild & that was a LOT of fun :D I would suggest a rail fence for your first one - I think it's one of the easiest patterns. I even made a pattern for the Rail Fence that my friend used to teach her *non-sewing* DIL how to piece & she said it worked. PM me if you'd like me to email a copy of it to you. :D
Good Luck - I KNOW you'll be great. :thumbup: