I'd go Victorian too, theres loads of info out there about it. God, I dont envy you lot, I remember doing the baroque etc Frizzytwig! I visited the Brighton Pavilion for my research.

Actually just had a look at the BBC gardening website, Georgian is good too cos you can touch on the gardening thing and how it influenced flower style. I remember writing a load of old waffle about Capability Brown and symettry. Another good page filler is historical paint samples that you can get from DIY shops. Sorry if you've done all this already!