...a valid PASSPORT (no identity cards accepted) that should be valid for the whole of your stay,...
...AND an electronic travel authorisation ETA.
An ETA is a digital permission to travel to the UK. It is NOT a visa and does not permit entry in the UK - it just authorises a person to travel.
Upon being approved, it is attached digitally to the traveller's passport.
The ETA costs £16.00 (April 2025). Be alert to UK ETA scams! Apply directly through the UK ETA app (or the government's website www.gov.uk/uk-border-control).
The application involves paying the fee (£16), providing contact and passport details, providing 2 valid photos (the one from passport and a new portrait photo) and answering a set of questions.
At the moment 34 countries require an ETA. The ETA lasts for two (2) years and allows multiple journeys and for stays of up to six (6) months at a time over 2 years.
MORE to know (spring 2025 until...???): Because of animal disease outbreaks you cannot bring meat (beef, sheep, goat, pork) or dairy products into GB for your own use - even not in sandwiches or dog food!
And what's about dogs? Your dog must be chipped, vaccintated against rabies, needs a pet passport and tape worm treatment.
And when all hurdles have been overcome: Just enjoy your holidays!
UK - EU deal in May 2025 - any news? We don't know yet, but we will keep you informed...