The insulation will be fine. If you kick it around, trample on it or disturb it at all you'll end up with a lot of dust in the air, so that's about the only thing to worry about.
I'd also recommend a grow tent. When you set it all up, try not to disturb the dust up there too much. I don't know what your attic is like but ours was absolutely caked in brick / mortar dust and other stuff. You don't want to breath all that shit in, or the glass fibers from the insulation wool. Maybe hoover up around where the tent will be going and then leave it to settle for a while; a day or two maybe. Dust mask would be an idea.
Set your tent up to pull in fresh air from around it and then dump it out into the house if possible. That'll stop your roof looking suspiciously hot through a helicopters IR camera. With a good carbon filter you won't smell anything.
Also have a think about what the climate is like around you. Before investing cash, put a thermometer in the attic and check out the temperature ranges. If it's 25C+ up there during the day, you'll need to really get your cooling sorted out to avoid heat stressing the plants when the lamps come on. If it can drop below 10C, you'll then want to think about a radiator (as suggested above). If it gets too cold, the growth rate will go down and you'll get chill burns on the leaves.