The registered office address is where Companies House will send any statutory documents and forms. The address must be in the UK and cannot be a Post Office Box address.
The address does not have to be a business address or the location where the company's business is conducted from, it is however important that the directors or administrators of the company have access to this location in order to respond to any instructions sent by Companies House. The registered office should also display a name plate on the outside of the building which is visible by anyone passing by.