Thanks.
I booked the BA flight from LHR to JNB on a 2 for 1 companion voucher using Miles, which doesn't allow for a same ticket booking on BA Comair as well. That has to be separate. Even if I book with BA Comair, I'd still need to re-check in etc.
May be better to book another flight, I'm just worried about driving from Port Elizabeth to Addo Elephant Park if it is dark...is this safe?