What Mr V says is true, though it is a bit more complex than that.
Foods that are classified as true food and not snacks are zero-rated. Which is why biscuits, choccy bars are always charged VAT.
Foods that supplied to eat-in always have VAT added because it is a service of food being supplied, not raw foodstuffs.
Foods that are heated will always attract VAT, even if you take-it-out, the supply is a service of hot food, even on a pasty that would be zero-rated when bought cold.