Hi pollyd
You will have to purchase a marriage certificate as it would be near on impossible to expect anybody to search all the churches and chapels in that area to find a marriage. In any case, if they married in a registry office then the only way to see the details is by purchasing a certificate as registry office marriage records are not open to the public.
John JACOBS - Rebekah WINSLOW
The ref is: Whitechapel, September quarter 1883 1c 703. You can purchase a certificate online for £7:
http://www.gro.gov.uk/gro/content/Once you have the marriage details, you should (hopefully) have the names of the bride and groom's fathers, names of the marriage witnesses and perhaps an address or two which might help locate them in the earlier census.
Good luck
Casalguidi