Alan - I don't think anyone can, or would want you to, stop you walking the course - it's on public roads after all. But if it is a cold/wet/ windy, or all three, day you may wish to tell the organiser you don't want a time otherwise you will be responsible for an army of volunteer marshals and results officials all waiting for you!!
Anyone watching this? Sorry, but what a dreadful programme; diminishes distance running further with its no-hopers building themselves up to be "heroes". What an awful waste of money (and my time watching this cr*p!).