the cloudprint plugin has a filter
$printers = apply_filters('wppizza_gcp_filter_printers', $printers, $orderId, $order);
the
$order
variable returns an array of order details where
$order['customer']['post']
includes the postcode selected (have a look at the full array, you’ll find the key that has the postcode)
based on that keys value , you could set the printer (i.e return the required
$printers
parameters) that’s supposed to be used
you’ll probably have to make sure no “Printer ID” is set in the cloudprint plugin settings (as that would override it)
not tested, but i think one could make this work