This depends on whether or not you have a finished or unfinished attic space.
Finished Attic: If your attic is actually a finished room with easy access, like a loft, then it is treated the same as any other room in the home.
Unfinished Attic: If your attic is unfinished then it most likely does not have any flooring and is difficult to access, usually from a pull down ladder. These attics make moving extremely difficult and unsafe, both for the movers and for your property. While most movers will not move items in/out of an unfinished attic space, the policy will vary by the mover. You should inform your mover about the unfinished attic when submitting a booking request. After submitting your request you should contact the mover directly to determine their policy about unfinished attic space.