I'd been worrying about moving up to secondary school in the UK for several years before I actually did so. Not the lessons, but the bells were the main fear factor. Luckily it turned out that 2/3 of the schools in my catchment area were bell free, so I got lucky. My current school has been bell free (well it does have fire alarm bells, not interval ones) since it opened in 1986, however this was a feature that was deemed to be too modern by a lot of parents 30 years ago, causing them to resort to a school several miles away with bells. At the school I go to, teachers do sometimes finish a little late (up to 5 minutes sometimes), which can annoy everyone, but there are other ways to resolve this than to introduce a bell in my opinion.
My primary school used a hand bell at the end of break times, but this didn't bother me because you could see when a teacher was going to shake it - it's not a constant clanging like an electric one.
I did some research over my town (Swindon) and found that of its 11 schools (13 in the catchment areas within), 5/11, or 6/13 have bells, which is just under half, however almost all of them have made the move in the last decade. In Bath, I wouldn't be surprised if there aren't any without them, given that all of those which I know of have them there.
Interestingly I became open of my fear of bells in June 2010, and Mackie Academy (according to Wikipedia) turned off its system in October of the same year for the same reason - and a number of others have since done so.
I get the impression that about 80% of all British secondary schools use bells, possibly being higher in America. Of newly built schools in the UK, this may be only around 1/3, though.
Do you feel that bells are a good idea or not in schools? Did/does your school use a bell, and are you bothered by it or not?