whereabouts do you live? if you live near Wandsworth Common you may run around it by whichever route you prefer and then cross over to Tooting Common? I do it the other way around, running around TC, then up Bedford Hill, into Ritherdon Road (downhill!), Balham High Road, Balham Park Road, Wandsworth Common. I was reluctant to leave TC as I wasn't keen on crossing big roads, but if you cross around Ritherdon Road it's doable - and the pavement is not as crowded as near Balham Station: I am rather dishevelled when I am running and I'm not too keen on being seen by people I know!