Seeking Buffyfic!

Specifically: years and years and years ago, way before I got as far as actually watching any significant quantity of canon, I swear I read a fic (possibly a crossover?) that involved Willow going to magic rehab in Oxford. The obvious terms to google aren't getting me very much of anywhere; I don't suppose any of you happen to recall it/have a link to it/etc?

(... it was worth a shot.)