I believe that the term Tomme means "cheese" and is the prefix for a series of cheeses made in the Savoy mountain region of France. That being the case I think it would probably be a sheep's milk cheese.
After further research it appears that "tomme blanche" is the early, white, unsalted version of laguiole cheese, it has a rubbery, springy, airy texture, very different from the butteriness of the matured cheese -and it is also a cow's milk cheese