Citizens of the European Union, the European Economic Area (EEA) and Switzerland wishing to travel to the United Kingdom will need an international passport from 1 October.
An identity card is no longer enough. The new rule is a result of Brexit. Until Thursday 30 September, all EU, EEA and Swiss citizens can use their national identity card to enter the UK. From Friday 1 October this will no longer be possible for most of them. Instead, they should be able to present a valid passport at the border with the United Kingdom. This must be valid for the entire duration of your stay in the UK.
There are some exceptions, including those who use or apply for the EU Settlement Scheme, those who received a family permit under the EU Settlement Scheme and cross-border workers.