One of the requirements of being employed by TSC if you did not do a Bachelor of Education or Diploma in Education course and you have a first degree in Bachelor of Arts or Bachelor of Science is that you must do a Post graduate diploma in Education(PGDE).
You must also have specialized in the particular subject you want to teach.
NOTE: Before you waste your school fees doing a PGDE, visit any TSC quality assurance department office and let them provide you clearance. TSC has recently started being strict on the degrees that can be attached to education.