Yo utilizaría este hook "actionValidateCustomerAddressForm"
https://devdocs.prestashop.com/1.7/modules/concepts/hooks/list-of-hooks/
actionValidateCustomerAddressForm This hook is called when a customer submit its address form Located in: /classes/form/CustomerAddressForm.php Parameters: <?php array( 'form' => (object) CustomerAddressForm );
Leeria el codigo postal y ejecutaria tu codigo