I attend the EIC Japanese language school in Reading, Berkshire (England). I had been studying Japanese on my own for about a year before I decided to attend classes. I rate them quite highly - all the teachers are native Japanese, and they change frequently (at least once every six months) to ensure you don't get too used to any one teacher. Every teacher qualifies first in Japan (at the EII school there) - and then gets to visit the EIC centre for a six-month stint. You usually get two teachers in each lesson - one will teach the material, and the other will scribble notes about you (as well as keeping an eagle eye on what you note down). Hidden benefit: You can be pretty sure your notes are accurate. If they aren't, you usually find out before you've finished writing them.
As is to be expected from a Japanese institution, they also go out of their way to help you learn. Although English is strictly forbidden in the classroom (even your notes must all be in kana/kanji - I personally find this helpful, as any practice is a good thing!), the teachers will resort to almost any means imaginable to help you understand what is being communicated. Just not English! Copious notes are taken, and lessons are often recorded onto tape - this is used to identify your weak points and coach you a bit more effectively. The teachers even go to the trouble of photocopying material they think you could improve on, walking you through a few examples - and then giving it to you to take away.
The teachers also have a FANTASTIC sense of humour.
Sometimes you'll get on really well with a teacher - and when he/she returns to Japan, you get a free penpal. This is also useful, as you'll discuss stuff you wouldn't ordinarily talk about in the classroom (even though I try to arrive early for each lesson - the small talk before we begin is always interesting). I've also run into words I didn't recognise and looked up, only to find them appearing in the classroom a couple of weeks later. Since you are prepared, it helps you make the most of your time in the classroom.
But, above all else, it's fun! You get an introduction to Japanese culture, and you can participate in events like speeches, calligraphy, etc. EIC has centres in England and Italy, to the best of my knowledge. The parent school EII is based in Japan.