As Jazz519 mentions above, tutoring centre for English is not worth it at all. I would go far to say that tutoring for english at a centre is useless, they basically teach things which your school teaches, additionally giving you a bit of material here and there. Majority of the tutoring centres do not give enough personalised feedback on your essays which is the most important thing.
But Ive heard good things about DELTA in their personalised essay marking service. But they are really expensive and may not be worth the money for what they offer as you can get the same service from a private tutor along with the individual attention that you need.
I attend Delta and can say that despite its high costs, the EPP's (Essay Perfection) is awesome because you can send unlimited essay's which come back very quickly with great detail in how to improve
As my trials are coming up after the holidays, i have spent a large proportion of my break looking through the booklets and writing notes for my texts so that I can memorise/familiarise myself with them and write unseen essays to questions in exam conditions
The booklets are very detailed and help a lot.
In saying this, unless you go to an organised centre like Delta where they know how to do it and give you many perspectives on the texts, a private english tutor may be feeding you information or marking your work which can be detrimental rather than helpful. It is integral that you develop skills to write essays early, with or without a tutor
I started to attend Delta during the middle of yr.11 and honestly, I should have just started in yr. 12. I was already competent in writing essays so Delta wasn't as beneficial as it is now. I can assume this same experience is common for many students.
If I have to give any piece of wisdom for english, it would be to work as hard as you can now, so that you can be in my position in yr.12, where getting great marks in english is simply making sure you are consistently answering the question rather than being in a struggling position where there are structural issues with your essays or incompetent analysis.
Delta is not the only one, so do your own research so you can make an informed choice.
In terms of Maths, try some out and get a feel for what you like. Parramatta, Fairfield, Cabramatta can all be good starting places.
For Sciences, I prefer structured learning so Matrix really helps in that respect.