If you are doing self-study, then the shop section of the ICB webpage says that the new Level IV Diploma books are due soon. Maybe it is worth ringing ICB to see when they are likely to be published.
I used the Kaplan books to do up to the old level III exams and started using them for the old level IV too. Recently I bought the new CPD book for the M7 exam, published by ICB, and it is very good.
Hope this helps.