Hi Helen,
The 'dittos' for the childrens names were all under Caroline Kimber on the 1851 census, so your Elizabeth may well have been registered as a Kimber, rather than a Craddock. Here's the 1841 entry for Caroline, I'm afraid that I can't find Benjamin.
ref HO107 474-14 folio 37: Minster Sheppey (no address)
Mary Kimber age 50 ind
Richard do age 21 labourer
Caroline do age 19
Thomas do age 14
Elizabeth do age 12
Hannah do age 10
Frances do age 2
Mary do age 7 months
all born in county
Mary (age 7 months), shown here may be the same Mary living with Caroline and Benjamin in 1851, Frances age 2 may also be Caroline's daughter, although she doesn't appear in 1851.
xx Carol