Pro tip, put water in your baking dish to keep anything that drips or leaks out of the abomination you created from turning to charcoal in the bottom

The only type of colonising going on in my bath are mildew and bacteria. Is this what the soap will do or should I just maintain my chemical warfare?

This, if the factory can do it then a skilled craftsman can as well. Talk to some local fab shops, I'm sure you can find someone skilled in AL welding that can fix you up