Sorry to hear about the rust. It’s a pretty common problem with VWs and can range from a minor fix to replacing the whole floor pan. I’ve had 2 bugs that needed such repair. Replacement floor pans are available from many sources starting at about $100. You can use part of the pan as a patch or replace the whole driver side. If it’s a small area you can cut out a patch from the replacement pan and pop-rivet or screw and seal without a trip to the welders. I’ve known of whole pans replaced with pop-rivets and epoxy sealer that worked just fine. While you’ve got the carpet up, check the rear of the pan near the engine, an area that usually rusts as well.
