|St Mary's Bures, Suffolk*|
Unfortunately the 1841 census is the only information we have about Sarah's date and place of birth, and it only tells us that she was born outside of Essex. Perhaps since she married James in St Mary's Bures, in Suffolk, she also came from somewhere in Suffolk.
At the time of their marriage, James' children by his first marriage would have been quite young - James about 7, Louisa 5 and Jeremiah 3. As mentioned before, it appears that Jeremiah died that same year, just before the wedding took place.
Sarah's first child, Sophia, was born at Bures and baptised at the end of 1826. Jeremiah (the second Jeremiah born to James) followed in 1830, and by now the family were living in Essex. Eliza was born about 1832, Harriet in 1833 and David in 1838, when Sarah was still in her late twenties.
At the time of the 1841 census James and Sarah had the five youngest children living with them at Wormingford. I haven't discovered (yet!) where James and Loiusa were in 1841. James appears to have married Lydia Stevens in Lambeth, London in 1845 and Louisa married Richard Springett in Colchester in the same year.
Then in 1846 Sarah's daughter Sophia married Charles Duncombe, who came from a large and interesting family (more of that some day). Did Sarah live to see her grand-daughter Mary Ann Duncombe, born in late 1847? Was she still alive when Jeremiah went off to America in 1850? All we can say is that she almost certainly died sometime before 1851, when she would have been in her early forties. (One family tree online says she died in 1841, but no source is provided.)
*Photo attribution: Bob Jones [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
see also An update on Sarah Baldwin