In the absence of any contrary provision in the company's articles (which is extremely unlikely), the registered office address can be changed by a decision of the directors. A board meeting should be held and a resolution passed to that effect. Any change in the address must be notified to Companies House. The change must be notified to Companies House on form AD01. This form can be downloaded from the Companies House website. If the company is registered for the Companies House webfiling service, the change may be notified on-line using that service. The change takes effect on the date the notice is registered, but any document may be served on the company at the old address until 14 days after that date (CA 2006, sec87(2)).
Incorporation Services Limited can provide a registered office service for your company.