Personally, i dont think English 'textbooks' are useful for the HSC, specially when about 80% of your work is based on pure essay writing + reading the texts. Just read and clearly understand your texts, write up mock essays, edit, more edit, get some friends and teachers to do more editing... Then come up with a few creative writing essays that are adaptable and you are well on your way to a band 5+ in Eng
None of the less, i dont think Excel is a great choice ://