I'm a little bit late with my updates (due to being quite busy this week), but I finally did W5R3 on Wednesday midday, in my (very damp) local park. I had a fantastic 3.7km session (including five minute warm up walks). I only stopped to lace up my trainers and to cross the roads between the park entrance and the main road.
To anyone on Week 5 or dreading the 20 minute run (I was the same): it can be done, as long as you go slow. And when it's finished, the elation feels incredible! I would've done a celebratory dance, but I was on a public pathway and there were lots of people around...
So now I guess I'm a runner? I certainly feel more like one than I did in the early weeks. Roll on Week 6!