I use tea in my hot process soap. I either use a commercial tea and I cut open the tea bags and steep the loose leaves in a small amount of water (from the overall water amount in the recipe) or I use my own dried leaves from my garden.
I don't use a regular "recipe", but I just take the water from the recipe and add the tea in the end, after cooking the soap, when I am stirring in the essential/fragrance oils.
I read in a book about using tea as the water in a recipe, so I tried making some green tea, then added my lye. It went very narley very quickly. The liquid turned brown and was sludge colored and smelled very, very bad. I'm sure I should have kept the temperature down or something, like with using milk, but I just mixed it together. Yuck, didn't do that one again. I just used the small amount of water and the tea leaves in the end.
Good luck!
I personally don't think the tea leaves add any exfoliating to the soap. They pretty much just come loose as you use the soap and that is it. I like the look of them suspended in the soap, I don't seem to notice a difference in the results with or without them. They are aesthetic and that it all.
I know that in cold process anything botanical can drastically change when the soap cures, but in hot process they stay the same and don't discolor.