Lufthansa Resource Technical Training at Kemble are very very good, I did all of my B1 & B2 modules with them. Generally they run a good selection of modules across the year, and often put together a zero to hero course.
Bristol College are meant to be good as well, although I have no direct experience with them.
A number of friends have used Barry College and found the training to be poor, although the study material is excellent.
Hope this helps