JamieJo - we posted at the same time so I just saw your post. Well done you!
I don't know what speed I go during the running times, but I enter my routes in
www.mapmyrun.com and it told me that my average spped for the whole thing was 4.6 mph. And I know I walk at between 3.25 and 3.5 mph so my running speed must be quite good.
Any running for me is a good thing so I'm not getting too hung up on the times and speeds - I'm just going at the speed that is comfortable for me and if it improves over time, I'll be happy with that. I covered 2.3 miles today in half an hour so that's quite good for Week 1 I think.
Julie - I know lots of people do the C25K on a treadmill.