4 pack of kronies, packet of Eccles cakes, type 2 sprocket undulator, lefthand latex glove and a Swiss roll, seems to cover most situations I have encountered
You want to be careful with those as if for some reason the police end up collaring you, which is unlikely but does happen occasionally, they may take a dim view of things that can be used to cut fences and suchlike.
As for my kit - camera, torches, alternate lens (just in case), power bank for my phone, tripod. Gloves and hat if it's cold. Water for drinks. Snacks for whenever. Anything else is immaterial to me and just added weight.