This is way up my "how I'm thinking these days" alley...
I'd try chemical destruction for the basic image... underexpose and overdevelop like crazy. Try really warm developer. (Shoot a little flat though). Grainy film pushed in warm rodinal.
Yep, learn to develop - you can do it cheap without a darkroom. Changing bag, tank and reel. (get a plastic reel and you can process a few frames at a time to dial in chemical processes).
Generational image destruction: Shoot (maybe as above); contact print the neg onto film to make a positive. Contact that again to make a negative.
Double expose subjects followed by textures like rough walls, etc. Make a black mask so the texture is stronger at the image edges.
Physical destruction: spray developed film with upside-down canned air (liquid-nitrogen-style frozen gas comes out). Wear gloves, use tongs or hemostats. Manipulate the frozen film or drop into hot or boiling water. (I have no idea what this will do, but the sudden and extreme temp change could cause cracks or crazing that's very organic).
Try burying film for a week, 2 weeks, 3 weeks after processing. Try to get mold attacking the emulsion. Could give you some crazy organic stuff. Water the "grave" with beer (many molds like it). Again, could give you some very organic effects.