Sparknotes saved me for my Year 10 Macbeth exam. I reckon it's awesome.

No, seriously, sparknotes is pretty good. And a 40 (8, 8, 7) isn't really that tough. Ok, put it this way, if you can write/analyse like Sparknotes in the exam, I really do believe that you can get more than a 40. IMO anyways.
For vocab, forget about those 8-10 letter words. In most cases, the simpler the better. Instead, you should try to learn to use terms such as decry, intrude, denounce, justify, detach, galvanise, espouse, disparage, encapsulate...words used to express the author's intentions. Try to be more familiar with metalanguage as a whole and you will be fine. Vocab is only a small part in the exam, sometimes I like to think of it as a hidden criteria, given that you can get 45 or above just as easily, if the ideas are good. GL.
If enough people ask for it, I can also get some essays from my English friends (low 40s to the mid-high 40s) and post it here in VN for everyone to have a gauge at.