Preferably, you need to make it possible for three-5h of transit time in Johannesburg, so that you have sufficient the perfect time to catch your connecting flight. Transiting in Johannesburg is very simple; only follow the signs for ‘Worldwide Transit’. The flight from Johannesburg to Harare requires about 1h 30m. https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/