I would do everything in my power to keep the cat out of the snake room, including putting a lock on the door so others people can't enter when you're not there. Your cat sounds like a high prey drive critter and if you're gung-ho on using a tank with a heat lamp, expect that cat to want to get on the tank at some point and the lamp will likely get knocked off onto the floor, which creates a fire hazard if the heat bulb or CHE doesn't break.