i did an essay on nights at the circus today- it was a close analysis piece. i think, amongst other things, i picked out gothic elements, post- modernist sympathies, and also feminist attitudes in the passage. i know fevvers is supposed to be pretty feminist- and you have the contrast between lizzie and fevvers- lizzie being a realist and fevvers nurturing her exotic imagination which is laced with magical and surrealist aspects etc.
hmm, i think if you do a close analysis piece- just 1 page- find something suitable, and you'll pick out lots of themes that you can then trace in other parts of the novel.