Well I'm back from my first run and survived it and managed to keep going. Found it really tough though and couldn't power walk in the recovery sections...I had to slow to a stroll. I think I found runs 3-5 the hardest and funnily the last one was a bit easier but I think that was because I was on the flat leg coming home and run 5 was slightly uphill as i was coming out my local park.
There's a few things to get right for next time. Firstly, I wore too warm a jacket but I couldn't find anything else to wear to tuck my phone into with a high enough pocket. I guess I need to buy one of those things to wrap round my arm and just go out in a tee shirt or light fleecy. Also, I'd been to a party and had a few drinks the night before and probably wasn't as hydrated as I could have been. Mistake.
I wore a heart monitor that I'd I bought a few years ago and used the mapmyrun app so I can keep check of progress in the future.
The most important thing is that I did it so that's a great mental boost and I've got a day to recover before I try again on Monday.
Postscript: once I'd got home and sat for 10m I was so stiff when I got up again. I think another thing I will need to do is to make sure I do some stretches or yoga when I get back home after a run.