The seller must charge and account for VAT at the point of sale, unless the consignment is a business to business sale and the customer has given them their UK VAT registration number.
To charge and account for VAT the seller will need to:

• know the precise nature of the goods to find out the correct rate of VAT to charge
• register for VAT – sellers that are already registered for VAT do not need to re-register
• keep records of the goods sold, and make sure they get accurate information to apply the correct VAT treatment to them

 

Source: Gov.UK website