Update: Tried. It was ok. I think I will do it - it's a 5-week training thing and I downloaded podcasts from the NHS website to use.
Today I did the first bit - which is a brisk 5minute walk, then 60secs running, 90secs walking until you've done 8 repetitions at which point you do another 5mins of brisk walking.
I had a bit of extra walking after that since I ended up at the shop to buy water and found I'd run SO FAST (?!) that my money had fallen out of my pocket. Thought about retracing steps but I'd wiggled around the park quite a few times and it could have been anywhere. It was only £2.00.