I can see you beating 3:30 fairly comfortably as you're definitely quick enough, you just need to control your pace a bit better.
I'm with you I enjoyed it far more the first time, not focused on time and just running to complete the distance. I probably went of a bit too fast but managed to...
Thats quite a story, I'm sure Channel 4 will feature it as I still can't work out if your incredibly brave or stupid! Fair play to you though a truly remarkable effort.