Found Egg Nog!! It's not just in Tesco, because we got some in ASDA (Clapham Junction) yesterday. It's a mid-size ASDA, so that means you can probably find it even if you're not near a gigantic grocery store. They are in the West Indian section in yellow boxes that look like juice boxes you put in kids' lunches. Very clearly labelled, can't miss 'em. We stuck ours in the fridge before drinking, but that's not technically necessary (the thought of warm eggnog, however, makes me feel ill). Is definitely runnier/waterier than American eggnog, but the flavor is still there! More something you'd have for novelty or our of desperation, but still cool to find. I think I'll be making my own again come wintertime, however, as this isn't the best substitution!