actually i think you will find you do need a driving licence to join now. They will allow you do the relevant tests which you would normally do before joining but upon passing these you will be told you need to obtain a driving licence before you can begin the actual training. I know this because my boyfriend has had to do the same thing and was given a maximum of three months within which he needed to obtain a driving licence. Without it he would not be allowed to continue with the training course.
Hope this helps x