Hi Sarah. I was after that Hummel as well, but ebay didn't send me a reminder and I missed it! I'm glad it went to a good home, and my student was happy to have a new copy, as her other two grade 7 pieces come from books she already has.
I'm working on this sonata as well at the moment. I played the last movement in my flute lesson last week, because my teacher doesn't know it and I thought it would be better to play it with the accompaniment so he could get a better idea of it. However, I'd suggest you work thorugh from the beginning, because the sonata makes more sense as a whole. And I think the first few bars are an absolutely stunning opening - I heard someone play this on the flute summer school I went on, and I just thought 'Wow'! Try seeing the whole piece as opera, and you won't go far wrong.
As for recordings, there's one on the Naxos website. I think you can hear the first 30 secs of each movement if you're not a subscriber, but I think paying the annual sub of $19.99 is an absolute bargain for complete access to their catalogue.