If Possible, you'll want to let three-5h of transit time in Johannesburg, so that you've got ample the perfect time to catch your connecting flight. Transiting in Johannesburg is rather simple; only Stick to the indicators for ‘Intercontinental Transit’. The flight from Johannesburg to Harare will take about 1h 30m. https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/