Whatever I found in some random petrol station, so Ginsters slice, McVities biscuits, bottle of water, Lucozade sport, sugar free redbull, flapjack, boost bar - whatever I managed to find really.
But I have standards so there's no way scampi flavour fries, some sort of hot dog looking thing of unknown age and providence, anything heavily reduced in a cardboard next to the till (because they couldn't sell it last year and they still have it) will make my list, nor anything unhealthy like sugary energy drinks or Yazoo milkshakes will make my discerning list.
Have been known to take a can or two of beer if it's not a solo trip and in great moderation (like one at start and one at end) but that's not often for me. (My avatar pic cropped out me holding a can of IPA)