The listed coordinates bring you to a Welcome Sign near the Cemetery gate.
To find GZ, A = Number of trees pictured in the Methodist section on the sign.
B = Sheet number for the Independent Section.
C = Sheet number for the Church of England Section.
D = Sheet number for the Presbyterian Section.
E = Sheet number for the Roman Catholic Section.
The container can be found at S35 05.(B + E) A A E146 36.(D - E) (B + E) D.
FTF locus cache congratulations Kaye.