I bought this software from WH Smith a while ago. It cost less than £20.
One disc is practically a carbon copy of the actual theory test. I found mainly the Theory disc useful.
Once you book your Theory test, you'll receive confirmation in the post, along with a DVD to watch. The DVD explains the testing procedure. For instance, you'll have to put your belongings in a locker before walking into the actual test room, etc.
I passed my Practical driving test in July, and there are two things I have found to be true:
Don't listen to relatives telling you what is required for the test and what isn't. If it has been more than 2 years since they passed their own test, all the rules which applied to them probably do not apply now.
And
From personal experience, independent driving instructors work harder than the BSM or AA people. Independents have to go out and advertise and work on building a reputation for being dependable. BSM guy made me feel like I was hopeless, when I knew that wasn't the case. 10 lessons with an independent guy, and I passed first go.
HTH
Laura
P.S. Also, if you wish your instructor to be with you in the car as you're taking the Practical, it can be arranged. It is standard practice to ask your driving examiner for permission for your instructor to tag along.