OK so I'm still on the treadmill but I run the full 20 mins and didn't actually find it as bad as I thought I would. Don't get me wrong my poor legs felt the brunt of 20 mins of my excess baggage and me pounding it, but the mind and breathing were all good. When Laura said 2 mins left I actually felt I could do another 5, however Laura knows best and tbh think the legs were glad that after a final 2 mins they were walking.
I would never have got this far I'm sure without reading all the posts and getting all the positive vibe and support from the lovely people on this site. Thank you all and for those with this week coming up, you're gonna be fine! And sense of achievement is amazing. Good luck to you all, will hopefully be doing my first outside run this week on my weekend away