This choral arrangement is available for purchase here: www.sheetmusicplus.com/title/.... Other arrangements by Jake Alexander can be browsed online at jakealexander.org/choir-scores.
Please note that this video features a recording of this arrangement in SSA voicing, which is substantially the same as the SAB version, and which is also available online.
Performed by Eleanor Rastall (www.eleanorrastall.co.uk).