If you're interested in studying Classics in Italy, have a look at the Greek & Latin Summer School run by the University of Bologna - more info here. I heard about it a few years ago, looks very interesting and I'm considering signing up for it myself - I'm in a similar position to you in terms of being half way through a gap year with very little planned!
The course you suggested actually looks really interesting. There's a big gap-year tour called Art History Abroad very popular among spoilt 'gap-yah' types and costs over £8,000 (yes, £8,000) for a two-month course. Compared with that, the British Institute is actually pretty good value so, if it's what you're passionate about doing, I'd say you should definitely go for it!
Last edited by Paddington Bear; 08-04-2012 at 21:58.