I was looking for these to.
AST do one, which is £4500 + vat, but they are the only ones who do a full B2 syllabus.
LRTT do modules 1,2,3,7,8,9,10 and 13. Prices vary dependant on courses
Ive not really looked at the B1 route
I know virgin do B1 courses...
Tbh, after doing alot of research, i decided the best route was self study, and doing the odd course for the ones your struggling with.
Though it depends if you want to work during this period or not, as i do not want to leave my job to do it. Obviously if your not working, then the courses may be a better option for you.
Heres some links to look at,
Lufthansa Resource | Technical Training | Courses
Air Service Training Perth UK aircraft maintenance training
Virgin Atlantic Airways - Popup
Hope these help