Huh. Sherry is unique because of the flor/film that forms on top during secondary fermentation under traditional practices, but that's not how sherry kits are done - much too complicated a process (more common yeast used during primary, flor yeast used in secondary). Sherry kits use EC1118 yeast, which does not form the cap, of course. That said, you are trying to make grain alcohol, so I don't see the connection to sherry at all - sherry yeast maxes out around 16% alcohol, while EC1118 can go to 18% or slightly higher.
Where's the recipe from? Sherry yeast is not commonly called for, except for sherry.