Say who you are
The Electronic Commerce Regulations 2002, regulation 6
Who it is for. Every business website. Government guidance says this includes a site that only tells people about a business and sells nothing online.
Show the name of whoever runs the business, a postal address and an email address, where anyone can find them easily at any time. For a sole trader that is your own name; for a company, its registered name.
Add your VAT number if you are registered, and your Companies House number if you have one. If your trade is regulated, name the body that regulates you or your professional body.
Any price you show must be clear, and say whether it includes tax and delivery.
What to do. Put these details in the footer of every page, or on a contact page the footer links to.