I reccomend contacting TransfairUSA (http://www.transfairusa.org
) or Fairtrade Labeling Organizations (http://www.fairtrade.net/
). These companies handle all the Fair Trade certification, and I am sure that they have much information.
The Makaibari Estate has a website that might be helpful, http://www.makaibari.com/
. Also, Anupa Mueller, the sister in law of Rhaja Banerjee, who owns the estate, owns and operates a tea room in New York. Her website is http://www.silvertipstea.com
. I've spoken with her, and she is very friendly. I think she could help you out.
Another option would be to contact Rishi-Tea. You've seen the travelogue for Yunnan. If you email them, you have a good chance of getting a reponse from Benjamin Harrison or Sean O'leary, gentlemen who have been there.
And Kevin from http://www.o-cha.com
can probably give you a ton of information about Japanese tea gardens.
I'm not sure what aspects of life on a tea farm that you want to focus your thesis on, but I'd sugest thinking about the effects of Fair Trade.
Hope you find what you're looking for.