Some turkeys will lay in a nest box if the box is big enough to accommodate them. Some will hide their nests out like guineas like to. Some will make use of a pallet leaned up against a wall for their nest site.
Once a hen goes broody, it is best that the tom not have access to her. A tom will take the fact that the hen is lying down as an invitation to breed. The unwanted breeding attempts can result in broken eggs, an injured or even a dead hen.
The tom can be removed from the pen or a cage can be built around the nest site with an opening large enough that the hen can fit through it but small enough that the tom cannot fit through.