It has been announced today that all non EU-nationals entering or transiting through the UK without legal residence rights or a visa. will require to apply in advance for an ETA (Electronic Travel Authorisation) costing £10 from 8 January 2025.
The system will open for applications on 27 November 2024.
This will be extended to cover all EU nationals (including Overseas Territories of countries which have them) from 2 April 2025- applications open on 5 March 2025. (Edited for typo). Citizens of the Irish Republic are exempt as they are covered by the CTA- Common Travel Area.
Each ETA permits multiple journeys to the UK for stays of up to six months at a time over two years, or until the holder’s passport expires if that is sooner.
https://www.gov.uk/guidance/check-when-you-can-get-an-electronic-travel-authorisation-eta