If you have two addresses that you use for business one where the business activities take place e.g. workshop, office then this should to be at the top so it is clear should they need to visit or write to you.
Registered Office Address
The registered office address is for limited companies only as they have a legal requirement to display this on letters, invoices, and emails. The registered office is where all the legal documents are kept e.g. company information, financial statements, payroll records and this is normally the accountants address not but always.
There will be mail that comes to the registered office address some is junk mail but companies House will always use your registered to send reminders for the confirmation statement and other deadline that are coming up.
You have to have this on all letters, Invoices and emails. One reason is so that a customer can check the number is official from HM Revenue & Customs.
This is for limited companies and it will be the number given to the company when incorporating (being formed).
Partners & Directors
You may wish to have partners or directors on your letters but this is your choice but is not a legal requirement.
You should have all your branding on all documents as the company identify you can also have all your social media addresses on their so customers and prospective clients can contact you.