As long as you've got a basic understanding, don't panic.
Once you get down there on the brush up course and Dick gets going it'll all become clear. I didn't completely understand it until someone stood infront or me and explained it. I found it much easier to understand that way than reading the notes.
You'll find the Bristol revision course covers the met syllabus fairly rapidly but comprehensively.
When you come to look at climatology at the end of the fortnight, everything slots into place and you will be able to tell where the wind comes from in Recife in January, and where the ITCZ, or Zone Inter Tropical as the French insist on calling it, is in July.
Promise, it's not as bad as it seems...
But if you're really worried give 'em a call, I'm sure they'll either be able to put your mind at ease or suggest something to help.
Best of luck