So kind of you to dig in and find these leads for me. I've been stuck on Sarah for two years, and its fantastic to make some progress again!!
I'm starting to think that Mary Nailard in Ash (nee Packham) is not Sarah Anns mother after all, but perhaps an aunt. (Bit of a cliche I know to send the unmarried pregnant girl to her aunt for the birth!). I'm thinking this because I have found three girls Elizabeth b1830, Fanny b1834 and Sarah Ann Packham b1836 in Ringmer Workhouse in 1841. Perhaps the family fell on hard times or the parents died and there was nothing else to do with the children.
Anyway, Sarah Ann and Fanny appear in 1851 living in Brighton. Fanny is unmarried but has a 3m old daughter. She is a dress maker, but I cant quite make out Sarahs occupation from the census sheet.