Ditto what everyone else said. It's not that hard. Particularly if you've done the drill with reaching down to loosen straps on toe clips. Good lord, how un-ergonomic is that?

The fall will happen the first time your brain is occupied with a dozen other things, and you haven't built the muscle memory/reflex to unclip yet. When prepared for a stop, it will be easy as pie. But one moment early on in your experience you may be running through a grocery list in your mind, simultaneously admiring a particularly nice view, when something occurs neccessitating an abrupt stop/foot down.

You'll revert to "old" muscle memory if you haven't built the new patterns, and that's when the fall, if it's going to happen, will. You'll just forget in that moment of instantaneous reaction that you are, indeed, attached to your bike.