I've only managed one 20 miler so far, and recovered quite quickly from it, fitting this run between Reading half and Hastings half. Thought I'd be wiped out for Hastings, but wasn't. However, this long run does include 4 stops for drinks! I will be doing the same run on Thursday and then tapering sharply. (last year a knee injury put me out of action for the last 10 days, but managed a 4.09 FLM on fresh, strapped legs). I think I must be completely mad, but need the long run for confidence.
GOOD LUCK on the 13th!