Hi, If you want to be a teacher, then go for it as you need a degree to qualify as a teacher - even if you have lots of experience as a TA. If you are successful in getting accepted onto a course, then it's because you are good enough. There is lots of support there to help and lots of people feeing just like you.
What have you applied to do? You could go and do a 3 year degree with or without QTS, but remember at interview, make sure you ask questions that help you decide whether the course is for you - not just whether they like you.