"Soma" is another tool of social engineering. It is vital for the economic imperative of the society that every class of human is happy and productive, following the motto 'Community, Identity, Stability". Think of it as 'chemical persuasion" It also helps to highlight how the obsession with technology leads to a regression of humanity(the main point behind you are arguing in this module).
I know all too well how shit boring it is, but really, there is no substitute for thorough digestion of the novel. Read and re-read Brave New World as often as possible, actually thinking as you read about such central critical areas as theme, characterisation, plot, point of view, language. Learn to take notes as you read-mark off key passages that convey thematic material or help to shape characterisation;jot down recurring images, metaphors, motifs;investigate the symbolic implications of speech;determine when narrative material is being presented ironically. If you can do all of this, you'll be able to place yourself in the top band easily. Believe me, going into an examination with a dodgy understanding of what's actually in the novel is suicide. Also, if you've read the novel more than anyone else, you'll be able to handle any wierd or unexpected question BOS might throw your way. Because ultimately, they are testing your ability to synthesise your information to meet the course outcomes.
That might all sound a bit daunting, but it's a good feeling when you know you've written a kick ass essay.