Are you sure you're classified as an international student? If you've been attending an international boarding school in Africa but have been returning to the UK in the holidays and your family have maintained an address here, then you would probably still be considered a domestic student.
If that is not the case, however, then your best option might be to move back to the UK for three years, get a job in the mean time and build up your CV, and then go to university when you're 21 and are eligible for a loan and domestic fees.