By all means know what "fish antibiotics" are useful and when. Those are almost the same as human antibiotics with slightly less testing for quality control and are a fraction of the cost and available without rescription. But taking antibiotics without medical training is nuts and acceperates antibiotic-resistance.

Many plants have antimicrobial qualities and many are in your meadow in your yard as they will pop up. Don't create sterile lawns of just grass. If you like that, realize that it goes to "seed" when not cut, thus a food source.

Grow medicinal plants. There are whole books on the subject. A physician in 1880 in America would grow an herb garden and collect medicinals. The go on a "circuit" on his horse and in his saddlebags were his and rarely her medicinal herbs.

The very first one you learn is honeysuckle which I discussed because while nonnative, it is available everywhere.

The other one that LOTS of our ancestors brought over from the old country was Common plantain ie soldier's herb and about a hundred names. That is almost certainly in your backyard. A smart six year old and a regular eight year old can identify it. That is antimicrobial, a plant that knits skin wounds together, a pain reducer, a burn treatment, slows bleeding.

Native Americans when irritated called it "white man's foot" ie the settlers came through here.

That herb saved soldiers since the ancient Roman legions.

Comfrey is in the category for very serious wounds and broken bones.

Garlic is in this category and so are onions.

A plain old pine needle tea that is brew strong as an infusion can treat a wound. Pine sap is an emergency bandage and though sticky will seal the wound and kill germs. You can find that old sap everywhere or make a nick and a blister of it will come out. Save an old dried hunk for later plus it's emergency fire starter.