101st/150 solo men at MM last year with 14 hours of actual riding, my one and only 24hr solo so far.
I find it just about impossible to eat during endurance races. Bizzarely, salted cashew nuts were all I could force down in any quantity. Find what works for you and take plenty.
I also find gels and sports drinks a bit sickly after a while. Take two bottles or bottle and camelbak so you can wash the sugar down with plain water if you get the same problem.
Take all the spare bikes and clothes you have got. I wrecked a tyre at Cheddar 10 hour, wobbled back to the start, swapped the complete front wheel off my spare bike and carried on. Much easier than changing a tyre.
Last year at MM, I was having a break after every lap. The breaks got longer until eventually I fell asleep. Epic fail.
I've done a few 12s, but I think the step up to 24 was too much.
This year I'm going to treat it as an 18 hour race.
Rather than ride for 12 hours, then get demoralised because I can't face another 12, and give in, I'll try to keep going for 18.
After 18, it'll only be another 6 to go.
I don't know if that will work, but it's worth a try.