As the marriage took place at a Presbyterian church (non-conformist) the only place you can see a copy is at the local register office or the GRO. Before 1898 non-conformist marriages had to have a registrar in attendance, in addition to the minister, to record the event in a Register office marriage register.
Until 1898 the registrars copy of a marriage certificate is probably the only one available. After that date Methodist marriage registers usually begin. Methodist marriage registers are closed to public access for 30 years.