Plymouth Leander’s Fannon and Sheffield’s Clogg complete the 45 strong squad competing in August after impressing selectors with strong performances at the Commonwealth Games.
Chris Spice, National Performance Director for British Swimming, said: “Tom and Elliot both add something new to the squad, not only as we head to our benchmark meet of the year, but also as part of our development plan for Tokyo 2020.
"Glasgow 2018 will give our entire squad the opportunity to perform on the international stage in front of a home crowd, which will test not only their ability in the pool but in the arena too."
Twenty-year-old Fannon, a sprint specialist, already has a European bronze under his belt – winning the 50m freestyle in 2016. Backstroker Clogg, 19, has also experienced junior success, taking the age group title over 100m in 2014.
The duo were called up after Lizzie Simmonds and Camilla Hattersley were unable to take up their places in the squad.