For a half marafun, I don't bother with gels, just take whatever sports drink or water is going at the aid stations. Might have a small energy bar before the start if I feel peckish.
For a full marafun, I carry two non-caffeine gels on the right of my race belt and one with caffeine on the left to give me a boost at around 30km. I take the first one about an hour into the run and the second one 30-45 mins later. If there are bananas or stuff at the aid stations I sometimes skip one of the gels. I used to have just a slice or two of toast for breakfast but nowadays I have a bit more breakfast, helps keep my pace in check for the first half hour or so
No-one else would have spotted me so I'll just have to spot myself. Finished my 14th IM distance race in sunny Korea last Sunday. Hooray for me! Yes, it was sunny, roasting hot and windy with some great bodysurfing just before the swim start!