Is anyone aware of any sites that may contain information on English marriage certificates? I have found some info in the marriage index but would like to confirm if these are the right people through the information on the certificate.
No. But if the couple were married in a church sometime during the last 200 years the parish register will probably contain much the same information as a certificate. Parish registers were often pre-printed in a certificate style format and filled in by the priest or clerk.
Unfortunately the General Register Office increased the price of certificates a couple of years back, also removed the pre-checking facility, so if you're searching for a couple with a popular surname it can be an expensive business!