I don't think op is saying she doesn't want to train, just aaking if she needs to do a full maths degree. Schools are looking for people with the potential to be outstanding teachers. They will look at the content of your degree and A-levels to see if you the right knowledge.
Do an Internet search for the governments train to teach initiative. Once you have worked out what subject you can teach you will then need to do a pgce or in school training programme like the gtp.
A friend of mine has recently got a job teaching English with a sport science and drama degree and post 16 pgce which she is converting to 11-16 pgce.
You can do a 1 year subject knowledge enhancement course, followed by a PGCE as it is in a shortage subject.
With a nursing degree, you may otherwise be able to get on a science pgce with biology as your A'level specialism.
I know a few people who have had humanities degrees and did subject knowledge enhancement courses before taking maths or science pgce's. I also know a few HCP's (physios, OT's not nurses) who did science pgce's on the back of the biology content in their first degree.
Speak to a few training providers, as some are more prepared to consider unusual backgrounds than others.