Thanks for the advice guys. I do tend to be impatient with my training and in Comrades tried to run the whole way which was a disaster. Sorry to go on about it, but its from past experience of my running exploits. I have had more failures than successes and long ultramarathons are new to me.
Some of these guys have exceptional acheivements in the Comrades, under 7 hours for a silver is excellent. I lived in SA for thirty odd years and knew Bruce Fordyce 9 times winner, but only when his career was finished and I belonged to the same canoe club as him. I have tried three times with 1000 miles training from jan to may and only managed 10 hours. There is a beginners program called the Oliver-Tabkin, in its 22 year history 95% of the estimated 6500 novices who followed the program finished in sub 11 hours. Total training for 28 weeks is 1781 Km. Look up Don Oliver and Dennis Tabakin, in 1979 they had 37 medals between them. The UK has some exceptional ultra runners, far superior to the marathon.