HI Julie, the best way is to get miles on your feet as it is a long way! I personally take no notice anymore of the marathon training schedules. There is the 50 mile challenge at this link which you could enter and see how far you can get: http://www.challengehub.co.uk/about-challenges/about-50-mile-challenge I did it last year as a warm up and you could drop out on any lap if you are at your limit. But it does give you a feel for the event's distance. The actual run in September is more terrain once you are out of the metropolis.