What procedures are available for 'patching' a perforated septum (quite large) left from surgery for a deviated septum?

Perforated septum. the options for treating a perforated septum are wearing a septal button to block the hole or to undergo surgical repair. Have your nose evaluated by a board certified otolaryngologist,
Local tissue grafts. Typically they take fascial tissue eithe from your thigh or from a cadaver; elevate the lining on both sides of your septum and down onto the floor of your nose. Then they put the fascial tissue over th hole on one side and tuck the edges under the elevated lining. They then slide the lining up from the floor of the nose and sew it in to place.
Not many. Very large septal perforations are often impossible to close surgically. You might be a candidate for a septal "button". This is a soft plastic implant that covers the perforation and is helpful for some people. It is important to keep your nose moist with saline spray and perhaps some ointment. Discuss this with your ENT surgeon.