We can support you if you are visiting Guangdong and Fujian province in south China.
From a travellers point of view, I would check out the forums on Lonely Planet - they are frequented by more people that have been in your situation - a lone foreign female traveller in China (for the first time?).
Where you are going depends on how many problems you will come across. Are your suppliers in First Tier Cities, or in second tier cities or rural places?
In First Tier Cities (Beijing, Shanghai, Guangzhou and Shanghai), people are more used to dealing with foreigners, but by no means could you describe the standard of English as "good". However, you could possibly get by alone, by getting a Chinese speaker to write addresses in Chinese and you can show these to taxi drivers.
I'll also warn you to expect a few culture shocks with the food. Rather than risking offending, you may want to make up some dietary condition, which will give you the right to refuse certain foods! The more of a delicacy, often the less appealing to a Western.
For finding interpretators, I would do so via expat sites such as AsiaXpat or MoreHangzhou - depends which cities you are visiting. People found via these sites will probably be marginally more expensive, but you're getting a guartaneed quality, as opposed to going directly to someone who hasn't been referred.