Vaughan William's Fantasia on Christmas Carols is well-served on a number of fine recordings.
David Willcocks' classic reading with the Choir of King's College, Cambridge, and the soloist Harvey Allen is still available on a budget priced Decca double-CD set titled "Noël: Christmas at King's." This is the version with organ and strings rather than full orchestra, but the singing is King's College Choir at its best and the ~50-year-old recording still sounds fresh and atmospheric.
John Rutter's excellent version with the Cambridge Singers and the City of London Sinfonia presents the version for full orchestra (Colleguium CSCD 512). Baritone soloist Stephen Varcoe is lighter than Allen, and though the acoustic is rich and resonant, it is less misty than the version at King's, allowing the textures of the orchestration to be revealed with compelling clarity.