I have done a couple of small weddings, and like you I was a little nervous. You will be fine! You do not need a lot of fancy gear--pretty much a camera, flash (if you don't have a battery pack, change the batteries whenever there is a break in the action so they are always fresh) and a decent zoom lens, hopefully with wide angle and you are good to go. I agree with Kilby's Mum, the candids are the best. I think it is best to get a good idea of the family dynamics beforehand. Try to know who is who.
I was at my nephew's wedding, offered to do it, but they wanted me to be a guest. Their photographer set up a second strobe light off camera near the dance floor. The idea was good, get some extra pop on some of the dance shots, but what he ended up with was a lot of pics with big light flashes in the backround--they were horrrible! Anyway, the moral of that story is to keep it simple your pictures are beautiful already so no need to try out something totally new.
One other thing I like to do is get the bridesmaids on my team. Talk to them ahead of time and ask them to let you know if you are missing anything. They usually know everything and sometimes there can be those little surprises at weddings. I also like to take a lot of wide angle "backround" shots--you know things like the flowers, glasses, table settings, invitation, outside of the church--They make for great backrounds if you plan to produce some composites. Good luck I am sure it will be great!
Bailey & Blake & Lucy (waiting at the Bridge)
Fred, brindle boy
Noel, fawn girl