A search on google shows that Mary Ottaway was a devout Catholic, so she’ll be in a Catholic section somewhere.
GRO birth index shows her mother’s maiden name was Sharkey.
There’s a marriage in Sheffield for a Joseph W. Ottaway to a Mary Sharkey.
If you look at the burial records on this site, Joseph and Mary (Sharkey) are buried in the Catholic section at Abbey Lane.
What’s betting that Mary Ottaway was either buried with her parents, or is at least in the same cemetery.