Well I type this post with a huge grin on my face, because I've just completed my 20 minute run! I wasn't sure if I could do it yet, but I put faith in the programme and refused to give in no matter how much my legs wanted to stop!
I am still running at a slow pace (google maps tells me I ran 1.4 miles which is 2.25km and quite a way from the eventual target...but speed can come later!) but now that I know I can do it I can probably pick up the pace a little bit as my breathing was still in pretty good control all the way to the end.
I feel really good about the progress I've made (who would believe that a month ago I was puffing my way through 90 seconds of running!) and really looking forward to completing the programme. Now that this barrier has been broken, I won't let anything stop me from reaching those 30 minutes!