The Derry Girls actor has always loved food, so who better to take over as the new presenter of the Guardian’s Comfort Eating podcast? Siobhán McSweeney is teaching me her preferred way to enjoy a packet of cheese and onion crisps. She has arranged two matching slabs of Cadbury’s Dairy Milk chocolate, two piles of Tayto crisps and two cans of Guinness on the table in front of us – and is issuing …