Hobbs was born in Hillingdon, near London. He was a junior exhibitioner at Trinity College, London, then was Cornelius Cardew's first student at the Royal Academy of Music from 1967. Hobbs worked with Cardew and Christian Wolff: he joined AMM, appearing on two albums: The Crypt and Laminal. Hobbs was Director of Music at Drama Centre, London from 1973 to 1991. He has taught at Leicester Polytechnic (later De Montfort University) since 1985. He is also Associate Senior Lecturer in Music at Coventry University.