Thanks for your replys!
I'm about to enroll in a distance learning course at one of the two distance learning schools here in germany by the end of this year. However, at least that's what i have been told, both courses have considerable flaws in one or another way, so i was looking for good set of books to supplement the manuals i'll get from the school.
I just had a look at the oxford webpage and found, surprisingly, that their distance learning course offer is in fact cheaper than the course here in germany i wanted to do, so i'm thinking to enroll in their course. Just have to check if it's not a problem to do the theory in the uk and the CPL and IFR training in germany.