If possible, you ought to enable 3-5h of transit time in Johannesburg, so that you've sufficient time for you to catch your connecting flight. Transiting in Johannesburg is very effortless; just follow the symptoms for ‘Global Transit’. The flight from Johannesburg to Harare can take about 1h 30m. Review Each https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/