Thanks again for all the comments. They're nice to read.
It's actually quite hard to eat and drink as much as your body needs on a big day like this. You're so focussed on just getting through it that you forget the needs of your body. I had to force myself to eat and drink. I must have consumed about 5000 calories that day, and drank about 6 litres of water. Even that wasn't enough...
Mancunian, that water looks cold! Your mate is hardy for swimming in all that snow-melt.