With the introduction of custom fees post Brexit, I have had to increase the visibility of how these charges are the responsibility of the customer.
As such, the best option I have found was to add a message to both my cart and checkout page based on the Shipping country.
In this example, I have a message displaying for ALL countries but United Kingdom, Isle of Man, Guernsey and Jersey. You can change the countries to exclude by using these WooCommerce Country Codes.
Before you make changes to your functions.php file, make sure to backup your website.