Hi,
As to whether you need to charge VAT will depend on the nature of the goods and where the goods are at the time of the supply. If the goods are within the UK when sold to customers, then the VAT liability will depend on what goods they are, the majority of goods in the UK are at the VAT rate of 20% but there are exceptions. You can see guidance here:
Zero rating, reduced rating and exemption
If you sell goods from overseas to the UK and the goods are over £135, then whether you charge VAT will depend if you or your customer is the importer of the goods into the UK. If you are the importer of the goods then you will be making a supply in the UK and will have to charge the corresponding VAT on the goods. If your customer is the importer of the goods, then they will pay the import VAT at the border.
If the goods are below £135 and they are being imported into the UK then please see the guidance here:
Changes to VAT treatment of overseas goods sold to customers from 1 January 2021
Thank you.