+1 on the training and nutrition comment, I've had a few pieces of good advice over there.
Not sure if you'd be eating during that ride though -- it's not too long in duration, and it's definitely not as easy to eat while climbing IMO. Since the energy content of a gel is pretty similar to a bottle of HEED etc., I'd go with calories from a drink during the ride.
Enjoy the challenge - I can't make it this year, but I'd like to get in for next yrs event.