Gavin studied composition at Colchester Institute under the guidance of Alan Bullard. At the age of 18, Gavin had his first piece published, a short piece for saxophone choir called "9:05 Rush Hour Traffic". Gavin has also written for orchestra, mixed ensembles, and choir. After leaving Colchester Institute, Gavin studied Screen Composition at the Royal College of Music under the guidance of Jo Horowitz and Frances Shaw. Gavin later went on to train as a teacher at Canterbury Christ Church University College, and has taught in various schools in Essex and East London.
Gavin has composed music for various projects in conjunction with students at the Royal College of Art and Goldsmith's College, London. His various projects include composing music for "The State of Things" animation which was shown in Paris and Prague, the radio play "Tiny Spiders which was shown on LBC Radio, "War Suite" written for an art exhibition commerating the 80th anniversary of Armistace and incidental music for a production of "Pride and Prejudice".