I went to the track at Sportcity a few weeks ago. It was on the Friday night of the Olympic opening, and my husband and I were the only people there. They have clubs and events on Mon-Thu, although you can train alongside some. Fri-Sun seems to be open to the public, though they advise you to phone and check. I'll certainly be going back (I'm out of the country at the moment). I think it was £3:50 each