I have just completed 8 out of the 12 modules to get a B licence from a A licence. I have left engineering now and was wondering the same thing so I contacted the CAA. They said basically after August 2012 you will have 10 years to get all your modules, get all the practical experience in a PER book and apply for the licence. If you have not completed all of the above in the 10 year period your modules will start to expire. This differs from the past because as long as you got your modules within 5years they never expired.