Flight time: Flights to South Africa from the UK typically take just over 11 hours. Direct flights are available to Johannesburg or Cape Town from London. From other UK airports, and as cheaper alternatives from London, you'll usually connect through hubs in Europe or the Middle East.
Transfer time: Once you've landed, transfer times vary by destination. From the OR Tambo Airport, you can take the Gautrain into Johannesburg city centre in about 30 minutes, while shuttle buses, taxis, Uber and Bolt take more like 45 minutes, depending on exact destination and traffic. Cape Town International Airport is about 30 to 50 minutes by taxi or app-based services to the city centre. Some hotels can arrange a pickup service, so ask about this when booking.
Price: The Gautrain fare from OR Tambo to Sandton is R219 (€9.50), plus connection into the city. A taxi from Cape Town Airport costs R300–R600 (€13–€26), depending on the destination and traffic, with similar prices in Durban.