You may need an ETA for South Korea if you have a British passport

Visa-exempt travelers from select nationalities have the option to apply for a South Korean Electronic Travel Authorization (K-ETA) until December 31, 2024. Although not mandatory, travelers who acquire a K-ETA are not required to submit an arrival card at the port of entry. Beginning January 1, 2025, travelers are required to apply for an Electronic Travel Authorization (K-ETA) before travel. Travelers can apply for and purchase a K-ETA entirely online. Once the application is approved, travelers receive their K-ETA confirmation electronically. This travel authorization requirement doesn’t apply to the following travelers: -Travelers who transit through South Korea and stay in the airport transit area without going through immigration control for any reason; -Travelers aged 17 and under and 65 and older are exempt from requiring a Korean eTA, but may apply to receive the benefit of not having to complete an arrival card upon entry.