Hello Julie,
Well, as you've posted on the Suffolk board I'm guessing your Hannah was a Suffolk lass! If so, then I can find only 2 Hannah's with parents John & Diana baptised in Suffolk over the period 1780 +/-5. One was Hannah Slater, who was baptised 7 March 1779 Glemsford St Mary. The other was Hannah Ward 22 Feb 1778 Baylham St Peter. (But that, of course, is assuming Hannah and her parents were Church of England. If she was nonconformist then it's a totally different ballgame trying to find her.)
Does either of those names ring any bells?
Birtle