Got to Stevenage this Saturday and took the train back. According to mapmyride gps that was 27.63 miles it certainly felt like a lot more. I think I've got the hands/wrist pain sorted with the extra foam on the handlebars, but by mile 25 my crotch was hurting in places I didn't know existed;-)
The big event is October 14 so I'm not sure I'm going to be ready. Still, plan to top up on the lifecycle during the week and get the miles in on Saturdays. So far family being very supportive of my disappearing act.