The Commodity/Tariff Code serves to identify the nature of your goods, and is required to facilitate transport of goods through customs.
If a Commodity/Tariff Code has not been correctly supplied, this may result in a shipment experiencing a delay at customs.
We would advise that you also check whether you are liable to pay any charges/taxes/duties when shipping internationally.
There are hundreds of classification codes. If you don't have one, you'll find more information on the GOV website. The classifications are very specific and must be accurate, so search thoroughly for descriptions.
You can email the HMRC Tariff Classification Service at email@example.com.