Limit Phone Number Digits for certain countries

Hi,

I am using this code to limit phone numbers to 11 digits for DPD shipping, however, other countries outside of the UK need more digits… I can’t seem to tell the field to look out for the country and if GB then, and only then, run the rule…

My working code so far…

// Limit Woocommerce phone field to 11 digits number
add_action('woocommerce_checkout_process', 'my_custom_checkout_field_process');
  
function my_custom_checkout_field_process() {
    global $woocommerce;
  
    // Check if set, if its not set add an error. This one is only requite for companies
    if ( ! (preg_match('/^[0-9]{11}$/D', $_POST['billing_phone'] ))){
        wc_add_notice( "Please enter valid 11 digit phone number."  ,'error' );
    }
}
//FINISH LIMIT PHONE NUMBER TO 11 DIGITS