Teetime, if you have a Decathlon near you, you can find very good value running shoes and a guarantee that you can try them and bring them back if they don't suit.
jane I didn't have time to read right to the end of the article. I do agree that the focus on women's bodies is offensive but of course, it reflects the way women are viewed. On the Woman's Hour programme I mentioned, one woman who described herself as tough and professional related an anecdote about being out running and being verbally abused by a man and she ended up in tears at home and didn't go out running again for two weeks. I suppose that's why the main thrust of the campaign is to encourage women to exercise in order to overcome 'the barrier of judgment'. Isn't that though like trying to make you give up chocolate by talking about chocolate?!
Women who are overweight tend to already feel bad about their bodies, it doesn't help to emphasize wobbly bits in an ad. I'm actually qualified to teach adults to cycle and I teach exercise classes too. I think there are lots of other things to consider - in my experience, many women lack confidence to go out of the door, let alone to join a group of relative strangers and be confronted by being asked take part in activities that may make them feel uncomfortable in body and mind. If they come with a friend and come often enough to realise that they feel better in various ways (brighter, less stressed, slimmer, more flexible, coordinated, making friends), then they'll usually stay. Also, the key thing is that exercise should be enjoyable, it's not good forcing someone into an exercise that just bores them to tears. Jenny Murray is an unabashed couch potato and is always funny when she talks about how it just isn't for her. And who's to say that if she enjoys life, it matters? 
Having looked at the actual website though, www.thisgirlcan.co.uk/, I'm grinding my teeth!