- You can get padlocks & even handcuffs with timers on them, some of them are pretty heavy duty, if you don't want to make a trip to the hardware store you can order delivery online.
Combined with a strong cellar door (or a heavy duty steel security door if you must) & there really shouldn't be a problem. Just be sure you put all the tools out of the room before locking yourself in.
None of that stuffs particularly expensive & is pretty easy to get hold of.
- The other really obvious precaution is to really pig out the day before the full moon, you've said they're psychologically like ordinary wolves during this time & wolves don't hunt when they're stuffed.