You want to have quality metalwork screwdriver tips. Whatever screw is used (take a look)... this will do-
The Wheeler Space Saver Gunsmithing Screwdriver Set takes up very little space on your bench, but contains a durable and comprehensive set of 26 bits...
www.midwayusa.com
for $17, that will go a long way for many of your gunsmithing applications to help you avoid "boogering" a screw.
I watched a lot of Mark Novak youtube videos as he repairs and refurbishes firearms, I also picked up a few valuable tips. Like.. tapping the properly fitting bladed screwdirver into the screw head to get very solid engagement. I suspect for the butt pad this is simply not a big deal at all.
Once inside, you're going to need to loosen Bolt L12. It appears that it may be a Socket Head cap screw. It might be a hex head. In any case, it's sure to be metric, and nine out of ten times exactly what you don't have in your tool box. You'll have to look in there with a phone light and see. Or an old fashioned flashlight.
The good news is that these are common inexpensive hardware store items. Poke a stick down and measure how long the shaft will need to be.
If a hex head, you'll need a metric socket head... probably 11 mmm, maybe 10 mmm or maybe 12 mmm or I am totally just plain wrong. Ask a clerk if you can return the ones that don't fit. You'll need a 10" socket extender. If you have a socket wrench, great. If not, you can get a small "key" (fancy word for square bar stock) (In Murrica it's going to be 1/4" or 3/8") about half an inch long that fits in the socket end of your extension and then you can use a crescent wrench. If you don't have that, buy a cheap socket wrench!
If a socket head, they make metric socket head fittings for your 10" extender but your local hardware store may not have it. Amazon is your friend, in this case.
Once you get the stock off, you'll be a Master of the Double Badger.. and you should post some photos and explain what tools you need!!! Then the next guy will know!