Tutoring isn't essential - it's aimed for students that happen to lag/struggle behind academically, however some who are capable use tuition as means of improvement and motivation (e.g. acceleration). There are other options aside from visiting a tutor, such as learning the content yourself. Tutoring pretty much requires effort from both the tutor and the student.
From what I've heard and experienced, here are some good maths tutors: Truongs (Ngo & Sons), Peak, North Shore
I'm not necessarily sure about English however; you can always have a skilled ex-English student, teacher or private tutor to review over your essays, creatives, etc.