not perforated 35mm is the basic ingredient for 126, and 828. Unperforated 16mm would be ideal for 110.
I wonder if the process allows winding rolls while bypassing the perforator.
I am not sure if they sold any of the uncut 120 backing paper last time. Cutting it down may work, but I believe that the edges get treated to make them conform to the spool, so just re-slitting 120 paper may not be sufficient unless the camera is loaded and unloaded in the dark. I understand that if Ilford had any 126 and 110 filling equipment it is long gone. Can't remember ever seeing 126 or 110 Ilford film in the stores here in canada