Hi
The GRO indexes are compiled from the quarterly returns submitted to the local register office and then to the GRO.
They are compiled in the order of Anglican church, alphabetically, the majority of which are available online, then Quaker, Jewish, and Registrar attended and/or Register office which are not available online.
The page range for this quarter is 1-210, your entry is at the top end of the range, 200, so I would suggest that there is very little chance of obtaining a copy online.
You might have to purchase the marriage certificate or birth certificate of one of their children to confirm the maiden surname.
Dawn