I still remember getting taken to watch the first London marathon when I was 10. Really want to be part of the first London cycle "marathon". Think it will be definitely something to remember and regret if you got a place and cba'd.
Camruns - I say ignore the "recommendations". I am only 5ft and weigh about 52kg. Most recommendations seem to be aimed at the average male. I would need only a couple of sips of water for a 2 mile run in the winter and I never use gels - they contain a high number of calories and seem a bit gimmicky to me (each to their own though). I think High 5 have about 300 calories which would take me at least 45 mins to burn off. A handful of percy pigs were more than enough to get me through a marathon.
I find that a lot of people's ideas about what's normal calorie and water intake are based on their own needs and they have no idea of the needs of a short person which are usually a lot less than the average male!