To make a customs declaration, you will need to provide a range of information about the goods you are importing, including:

The commodity code for the goods: This is a classification system used to identify the type of goods being imported. You can find the correct commodity code by using the UK Trade Tariff tool.
The value of the goods: This should include the price you paid for the goods, as well as any other costs associated with them, such as transportation and insurance.
The origin of the goods: This is the country where the goods were produced or manufactured.
Any special treatment or marks that apply to the goods: This could include information about whether the goods are subject to any special handling requirements, such as quarantine or inspection, or whether they are marked with specific symbols or labels.