I can agree about the oxford met cd - I thought climatology was going to be my undoing too, but the cd sorts it out really well. It appeared when I started reading the sylabus it to be loads of very complex and unrelated facts to learn but the CD builds from the top down such that you'll learn the basic patterns and then it teaches you build on those such that you can work out most of what's going on from those key flows.
When it came to the exams the questions on the subject were few and quite easy ones.
(I've got the same thing going on again, this time with electrics - but alas no instant fix from a CD... I'd love to hear from anyone else who's struggled with this and found a good reference).
Keep at it, if I can pass met anyone can.