While i would say get a qualified english tutor (as in HSC qualified) for your standard english subjects (2u english standard, 2u english advanced, 3u), and a writer for your 4u.
Extension 2 is really not standard english teaching - it is a creative process for which a writer will be more valuable to you as they are generally widely read and can pick styles and lack of flow.
I mentor four unit english, because i am a writer. I am entering my third year of a writing degree which is mostly made up of writing, reading, workshopping (both your own and other people's work) and developing styles in relation to other prominant authors over history. In addition, cultural studies is undertaken as a way to get 'background knowledge' into the culture in which you are writing, as well as the culture you are writing about.
I've already PM-ed about mentoring you, but any others who would like mentoring - please message also.