Guangzhou is very close to Foshan, Zhaoqing and Qingyuan. It is one hour to Foshan by bus, 1.5 hours or so to Zhaoqing by bus (trains are available too), two hours to Qingyuan. I suggest you go by bus, because it is more buses and convenient. If you have few things to do in Foshan, you can get back to Guangzhou the same day.