All businesses should prepare standardised documents for their correspondence and invoices. An invoice is basically a standard letterhead with the addition of a number of billing points. The examples set out here assume that your business is a limited company.
If you are a sole trader or if you operate as a partnership, you can ignore the bits about a company registered number and registered office address.
Your trading address must be included in all cases. If your company registered office and your principal place of business are one and the same, that you only need to show the address once, provided that it is clear that they are one and the same!
The legislation is set out here and it includes a requirement that you show these details on your web site and somewhere within your emails: