I can't believe anyone would ask a question that amounts to "ooh, this seems like hard work - can I do less and still get by?" If you really want the job, you'll read the two or three books on UK ATC and a Jane's spotter book, and you'll scour Flight International for any information that'll help. You wouldn't be trying to cut corners when separating aitcraft, would you?
Certainly though, your money is better spent on book than on quasi-professional exam preparation....