I'll tell you what I did, perhaps you'll find something useful...
I rewrote all of my notes, highlighted them and read them aloud to myself. For languages just read all of your speaking aloud as much as you can, a friend of mine recorded herself saying hers and put it on her iPod and it really helped her. As for Blood Brothers try to see a performance if you can. For the exam you need to bear in mind that it's a play, not prose. Also, check out SparkNotes, they'll have stuff on Of Mice and Men, looking at themes, motifs, characters etc, and get some study notes if you can.
I have to admit that I didn't actually do many past papers - but you ought to do at least a few, just so you know what the exam actually looks like, so you don't get thrown by it!
If you're struggling to concentrate, perhaps you're just overloading yourself with work? Reivise in short chunks, with lots of short breaks to help concentration. But you'll find that the more you revise the more you get into the rhythm of it too.
Someone told me that Polo mints are good for revision, if you have one in your mouth when you're revising and then in the exam have another it's supposed to help you remember things. I suppose it must be a sensory thing, or perhaps it's just positive psychology? Other than that - good luck!