Guy was born in Hampshire in 1991, and received his early musical training on saxophone and as a chorister in the Winchester Cathedral Choir. He studied at the Guildhall School of Music and Drama with Christian Forshaw, Nick Moss, Mick Foster and John Harle, also completing a masters degree with scholarships from the Countess of Munster Trust and the Guildhall. During this time he was selected as a finalist in the Worshipful Company of Needlemakers Woodwind Prize.

Guy is a founding member of the award-winning chamber group Kaleidoscope. Since its creation in 2009 the group has performed widely across the UK and Europe, including appearances at the Wigmore Hall, Bridgewater Hall and Purcell Room. The group has won numerous awards from organisations including the Hattori Foundation, the Tunnell Trust, the Worshipful Company of Musicians and the Park Lane Group, and released their first CD Oil in 2016 with support from the City Music Foundation and the Help Musicians Emerging Excellence scheme.

Guy is often called upon as a multi-instrumentalist, performing on saxophone, clarinet, flute and oboe in pit bands, folk and rock groups, as a session musician and in orchestras. Theatre work has included engagements at the National Theatre, in the west end and on UK tours, with recent shows including Aladdin, Fun Home, Gypsy, Chitty Chitty Bang Bang, Wonder.land and Thoroughly Modern Millie. His versatility has also led to freelance work with a wide range of groups and artists including Britten Sinfonia, Paul Weller, Public Service Broadcasting, The Magnetic North and Afrik Bawantu.
As a folk musician, Guy is a member of London folk-fusion band Tribe of Tinkers, performing at festivals and ceilidhs and regularly packing out venues in London and throughout the UK.

Guy is a visiting woodwind tutor at Northwood College in north west London, and regularly undertakes outreach sessions with Kaleidoscope for the Live Music Now scheme and the Worshipful Company of Musicians.