Members of a Parochial Church Council are also charity trustees, as all PCCs are charities.
The Archbishops’ Council, Parish Resources website has a helpful material on PCC members and what it means being a trustee.
The Charity Commission produce a range of publications to help trustees:
The Diocese has produced a Trustee declaration form for use by members of PCCs (updated December 2014)
There is further information about PCC charitable status, and also about the circumstances which trigger mandatory registration with the Charity Commission here.