Kinda like radoggair
1 x 750ml with tab, and extra tabs in case it get's super hot.
1 or 2 Elevenses bars.
I don't do that many 100 milers, but I don't bother with food on the more popular 100K rides so two elevenses is a feast.
Edit; forgot to ask. Can you manage malt loaf on the hoof? And I find Haribos clag up my mouth.
And breakfast about two hours before the 100 mile ride = 4/6 slices of jam on toast, any cereal, pint of tea and biscuits, and any bits and bobs laying around. That way I don't get any hunger feeling at all. That'll also see me through a 200K.