There should always be a person available, not (just) an employee handbook.
Obviously, but that person isn't omnipotent. Perhaps that person has never taken maternity leave and doesn't know the routines. Having things written down somewhere makes it easier to find and eliminates any guesswork.
The other advantage of a handbook is anonymity. Perhaps you want to look up the routines for maternity leave without announcing that you are/plan to be pregnant.
Obviously, but that person isn't omnipotent. Perhaps that person has never taken maternity leave and doesn't know the routines. Having things written down somewhere makes it easier to find and eliminates any guesswork.
The other advantage of a handbook is anonymity. Perhaps you want to look up the routines for maternity leave without announcing that you are/plan to be pregnant.