You don't say where you live, but it sounds like maybe in the western US someplace (national forest, coyotes, etc). If that's true the only dangerous snakes around are rattlesnakes. And they are certainly something to be worried about around the homestead. I don't think the chickens will attract snakes but mice will. So you need to be very careful not to do anything that will attract mice. The main thing is to not leave feed, like chicken scratch, open where they can get into it. Keep it in a good metal trashcan with a well fitting lid. And if any mice do show up, set traps and get rid of them. Also, don't let junk pile up. That provides hiding places for snakes, mice, skunks, and other vermin.
I know you have a snake phobia, and it probably doesn't do any good to tell you that most snakes are actually beneficial. The bull snake (AKA gopher snake) is especially good to have around because they eat mice and supposedly discourage rattlesnakes. Some people think they kill rattlesnakes. I think they probably out hunt them, and the rattlers can't compete.
Snakes and other varmints are a fact of life out in the country. Even if you don't have chickens, you may have snakes come around. If you do find a rattler around the place the best thing to do is to load a bird shot cartridge in your .22 rifle and shoot him right in the face, with the muzzle of the rifle a foot or so away from his head. This is very effective, and much safer than shooting a bullet at him, which can ricochet off and hit something else.
