What evidence do you have that Iran would almost certainly attempt a first strike?
Iran's rulers are well aware that any attack they launched on Israel would receive an overwhelming response. I don't buy into the idea that Iran's rulers are a bunch of manic religious nuts that will suicide their entire country just to kill a bunch of Israelis.
Sure, they don't like Israel, but their biggest concern is maintaining their own position of power. They see nukes as a deterrent to keep outside forces from removing them from power. That's not to say that it's a good idea to let them have them, but I don't think it's a doomsday scenario either.