Thanks for the reply Henky. MFU would be my first choice except for all the stories about lack of availability and the only option being direct to SYD. I will investigate the aus pass option.

Booking a RTW from South Africa is interesting but looking at the OW site this seems to be about £4.6k for 4 continents and I assume you mean book offline via AA ?

Any other suggestions still welcome. I don't want to splash this amount of cash and find out I've done it wrong