Wordpress woocommerce shipping payment change on postcode

function custom_override_checkout_fields( $fields ) {
$fields['billing']['billing_postcode'] = array(
   'label'     => __('Postcode', 'woocommerce'),
   'placeholder'   => _x('Postcode', 'placeholder', 'woocommerce'),
   'required'    => true,
   'clear'       => false,
   'type'        => 'select',
            'class' => array('update_totals_on_change'),
   'options'     => array(
        'E1' => __('E1', 'woocommerce' ),
        'E2' => __('E2', 'woocommerce' )
        )
 );
}
add_filter( 'woocommerce_checkout_fields' , 'custom_override_checkout_fields' );