The 204 & 206 exams are "centre derived", that is they are different at every college, devised to meet a C&G standard and approved by the C&G, so without knowing what you'll be doing it's difficult to advise you. Make sure diagrams use correct symbols and colours, get your stores list right and for your install you should know the standard required (terminations tight, no copper showing, fixings good etc) & check your OSG to make sure your testing is good. Sorry to be vague, good luck!