Primary school teacherWatch
If you already have your degree, the best way to gain QTS will be to sign up for a post-graduate teacher training course. There are several different postgraduate routes to QTS, you can check out the Get Into Teaching website for more information. Most routes will take a year.
If you haven't yet started your undergraduate degree, then you should be aware that there are undergraduate routes into primary teaching. Look for teaching degrees that include QTS. These offer less career flexibility if you change your mind about teaching, but might make more sense financially, as you won't need to be studying (and therefore taking student loans) for as long.
On a similar note, when applying for my nursing degree, my 3 A levels and previous degree didn't stop any university asking for proof I had GCSE maths & English before offering me a place.