It's also worth, in advance, working out what sort of food keeps you going (protein/chicken-based dinner means my legs are brand new in the morning for example), as eating the right things makes a big difference. That's more trial and error though, but you've plenty of time to try out a few days on the bike.
I'm hoping it'll be confit du canard and/or cassoulet for me, but I'm willing to give it a try.
Damn: I want to go tomorrow now, not wait until 2016.