Where in China do you plan to live? By south do you mean south-east (Guangdong and Fujian) or south-west. Cause they are very, very different places.
I live in Lijiang in Yunnan (south west of the country, bordering Tibet). It's the cleanest part of the country and since it's a tourist town it is possible to get most the Western foods I want when I need them. Other than big cities like Beijing, Shanghai and Guangzhou you're going to find that to be an issue.
I've been out here for 6 years now so I know China pretty well. If you've got questions, feel free to ask. I'm also an English teacher so if you need any insights on that, I can help.