As I said, that probably is the marriage you need, indexed under Lavins and Stanford Dec 1850...
Here's Ann with her parents in 1841:
HO107/890/23  Yarnton Village, Wootton, Oxfordshire
Thomas Savins  35  Ag. Lab
Keira        "        35
Ann 14, John 8, Susanna 6, Henry 5, Martha 3, Thomas 1
Barbara