Maths - practice gets you close to perfect. It really is just a matter of completing your homework and making sure you're exposed to all different kinds of questions. The hardest topics for most people is Binomial Theorem and Projectile Motion although I find Perms and Combs really hard as well. Parametrics is just a matter of getting lots of practice because it becomes a little mechanical over a while. Also yes circle geo can be hard - you may not do revision on circle geo in year 12 so I would advise doing self-revision on circle geo occasionally - probably not the best idea to cram it before the trials when it gets to crunch time. You don't need a tutor for maths tbh you only really need motivation, dedication to learning, and a helpful teacher. But it really depends individually - if you are struggling in maths and/or motivation, a tutor can give you the extra push.
English - Mod B usually the hardest because it's a critical study that relies highly on your personal interpretations of the text and also needs wide knowledge and understanding across the texts because the questions can ask you literally anything. But for english in general, write lots of essays, engage in the content and especially its philosophical ideas. You may end up enjoying english when you engage with the deep thinking behind each module ^_^