No, you really can't just wash off the wild yeast and bacteria, I'm afraid. There isn't any substitute for campden (which is also known as potassium metabisulfite). There are winemakers who don't use campden, though. They just sanitize, and hope that the yeast they pitch can outcompete any stray bacteria. Or, they do a "wild" ferment and allow it to ferment with whatever is on it. I don't recommend doing that, but I know that some do. In my opinion, you're more likely to have vinegar than wine without the campden tablets. They are available at every winemaking shop, and online.