Before B&W went out, I finished the game and roamed around with mods and god mode to have some mindless fun.

When I was done, I saved my game and waited for B&W to go out. At my surprise, my character is stuck in god mode (I forgot to deactivate it, it seems) and I don't know how to activate the debug console in 1.21. I don't have any early save when I'm not in god mode, I have a habit to delete old savefile when there is a lot of them.

I tried to reinstall the game with only the 1.12 version and HoS expansion but I can't. When I'm done GOG just tell me to finish the install, I can't play without B&W

I don't know what to do to fix the problem. Any help? Thanks.

Installing mods will have a lasting effect,this looks like a job for uninstalling all mods then try.If no change then it's uninstall game and do a clean reinstall and start a new game:-(

Every mods is uninstalled and I already tried to install pirated release of the game without the B&W dlc. Doesn't work because it's a save problem.
"Start a new game" isn't really a solution. I'm waiting for the mod to get updated and I try workaround for now. If someone has a solution, it would be nice.

Buy the game, thief.

So you didn't read?
My game on GOG has auto-update, so you can't use the debug console for 1.12, obviously.
So, I used a pirated release to go back to 1.12, but it doesn't work.
I DID bought the game, and preordered the season pass, moron.

Next time try to use your brain.

Edit:
Problem solved! I found a workaround.
For anyone having a similar problem: http://forum.cheatengine.org/viewtopic.php?t=581792&postdays=0&postorder=asc&start=0
Go there. Or, if the link gets deleted (I don't know if you can post links on gog forum) type cheat engine witcher 3 on google. When you get to the right thread (The Witcher 3 in Tables) download the table and install Cheat Engine (there is a tutorial on the forum if you don't know how to use it, it's very simple)
Check the debug console box and voila! The debug console works, I'm no longer a god, I can play the game just fine :D