To enter higher education, you must have achieved a National Senior Certificate for Degree or Diploma studies, or an NSC with endorsement. Generally you are required to have a minimum Level 4 pass in English as Home or First Additional Language, for English speaking institutions.
If you are over the age of 23, you may qualify for 'mature student' status, which means even if you don't have a Matric you can write an entrance exam to be admitted the institution.
Most higher education institutions offer some alternative access routes for students who have not met the entry requirements for specific degrees and diplomas. You can find out more about these programmes from the Applications office at the institution/s you are applying to. Generally, there are two types of alternative access: one where you complete a 'bridging course' before embarking on a degree or diploma, and a second where you begin your degree or diploma but the courses are spread out over a longer than normal period.