I’m in the same boat. I’m a bit of a diy dad too. Recycle cans and bottles to contribute to the car fund.
There are folks much smarter than me on here. Given the circumstances, I’d try to figure out how extensive the rust is. I don’t think you’d want to just glue the new panels in. If the rust isn’t too extensive, and you’re unable to weld, then you may be better off putting the carpet back down, or with a temporary fix like fiberglass, or a smaller patch with sheet metal screws.
Plenty of threads here to research, but the floors are part of the structure of the car. I waited for a few years, knowing that my floors were bad. Saved up to buy the welder and saved up for the pans.
A car mentor of mine just recently told me that license plate patches are okay, but if you’re going to go further and fix it, then you fix it right.