Do I have to inform Companies House if ownership of my company changes? Corporate & Commercial

Yes, you must inform Companies House by updating your ‘persons with significant control’ register within 14 days of any change in ownership.
Pre-June 2017 those responsible for managing UK companies updated their PSC register annually by way of an annual confirmation statement. However, changes to the regulations mean this must be done at the time the ownership changes to ensure the PSC register is always current.