This is what we know thus far:
If you have voted before, you are registered because your name would have – or rather, should have, stayed on the Voters’ Roll (VT).
If you have not voted before, chances are you are not on the VT. If you are slightly doff and cannot remember if you have ever registered to vote, go and check if you are on the VT at the IEC’s online gadget at https://www.elections.org.za/IECOnline/CheckIDNumber and pray it works.
If you are not registered you have the right to go to the South African High Commission in London, or at any South African High Commission, Consulate or Embassy and demand to be registered. They will not do this if you do not you’re your own green bar-coded Identity Document as well as a valid passport. Don’t send your auntie to do this. You need to do this in person and ask them for proof. You don’t want to go back every second week or end up going home all crying on voting day.