Maybe if the event was advertised as an "English Barn Dance", this would dispel any idea that it's American, and also suggest that it was traditional (ie not disco).

For a website, I agree it would be useful to include "Ceilidh" as well, but as there are alternative spellings (not to mention lots of wrong spellings), it wouldn't be sensible to rely on it, especially for people searching via Google etc.

Oh, and DON'T call it a hoe-down, or you will definitely get the "Yee-hahs" and the cowboy hats.

Marje