To become a high school English teacher there are maybe five options I know of
1. Bachelor of Education (Secondary) [BEd]
2. Bachelor of Arts, majoring in English [BA] > Postgraduate Diploma of Teaching (Secondary) - I think only the University of Melbourne offers this. Look
here and
here3. Bachelor of Arts, majoring in English [BA] > Graduate Diploma of Education [GradDipEd]
4. Bachelor of Arts, majoring in English [BA] > Master of Teaching [MTeach]
5. Bachelor of XYZ, not majoring in English [BXyz] > Graduate Certificate of Arts > Master of Teaching/Graduate Diploma of Education/Postgraduate Diploma of Teaching - This isn't very recommendable especially if you already know you want to teach English. It's more for people who start (for example) a Bachelor of Commerce then by the end realise they want to teach Drama/Biology/not commerce.
Going the BA/MTeach route wouldn't require you to have a Maths prerequisite, and I can't imagine doing a BEd (Secondary) with an English major would either.
The Graduate Diploma of Education is slowly being phased out of universities in order to work towards a higher quality of teachers in favour of the Master of Teaching.
Luckily you are surrounded by teachers so you could ask them what they think your best course of action would be. Also you could try messaging
Muuru for some advice