I didn't eat at all during my labour, but I will have some things ready if I want to this time.
I would suggest Walker's Oat Cakes; they are a bit like sawdust at first until you're used to them, so start eating them now if you'll consider having them around- and the Highland ones are easier to take at first than the fine oat cakes, ime, but the fine ones are easier to chew and will dissolve in your mouth whereas the highland ones are baked with whole cracked wheat and require lots of chewing. I am actually officially addicted to them since I finished off the first box a few months ago
Oh, the highland style has wheat and 1/2g sugar per cake; the fine oatcakes have no sugar or wheat, just oats, baking soda, sea salt and vegetable oil. They are not organic, and I really wish they were, but our choices are limited up here. Anyway, I can eat a few of those anytime and feel back up to speed again, and they are great for settling my stomach.
I'll also have lots of organic juice and pure vitamin C around. I really doubt I'll want anything else. Avocadoes might be a nice high-energy fruit to cut open and take by the spoonful- also so soothing to the stomach. Properly steeped Yerba Mate- full of nutrients, mild- not recommended for pg, but you'll be done by then and the reason is that it suppresses appetite by giving so many nutrients without caloric intake- dangerous for pg and nursing, but you won't be in danger at that stage and as long as you also take food if you are actually hungry, the yerba mate could just carry you through until you're done.
Just some ideas I've had kicking around on the same subject. I hope you have a wonderful birth!!!