A large collection of Alwynne's Pritchard scores have been archived at the British Music Collection at Heritage Quay and can be referenced further at the links below. I was particularly drawn to her work which encompasses more open compositional techniques, games, mazes, performance and choreography and in more recent years, photography.
Link to scores held at BMC: http://heritagequay.org/archives/bmc/?person=Pritchard%3B+Alwynne+%2815+Jan+1968%29