The Hannah Butcher baptised at Littleport in 1813 unfortunately was buried a few days later.
Baptisms for Coveney are available on FreeReg
http://freereg.rootsweb.com/ and you can sort out the 1841 family given by dragongirl from there.
It appears that Isabelle was the illeg daughter of Rebecca and not the child of William and Sarah.
A Hannah Butcher married at Coveney in 1841 and you can see the options for the groom on FreeBMD (December quarter).
A Sarah Butcher was buried at Coveney in 1836 aged 59.
Also found a Hannah Butcher born 2 December 1818 but she was of Waterbeach dau of James and Mary, non conformist and another 1816 at Chatteris, Wesleyan circuit.
Coveney looks the best match so far from the details you have given.
Regards,
Selina
Added: Following later census records it looks like the Hannah Butcher marriage in 1841 was to William Spooner. She appears to have eventually ended her days back in Coveney being buried there in 1901 aged 85. On FreeBMD the district for the death is Ely, in Cambs burials there is a Hannah Spooner buried Coveney 1901 aged
35 which I think could well be a transcription error.