There are several ways to qualify as a teacher, most of which rely on further qualifications. Work experience is often important in getting a place on a course of further study as well as in getting your first job.
Qualifications
There are several routes into teaching:
Work experience
It is helpful to have some experience of working with the age group you are intending to teach.
Local schools may use volunteers in after school clubs or as classroom assistants.
Talk to teachers at the schools you have attended, it may be possible to spend a few days as a classroom assistant to gain experience.
Organisations training teachers
Teach First is a charity running independent graduate teacher training in challenging schools, offering QTS through a short course in teacher training followed by on the job training in schools.