You will not be able to use an EU, EEA or Swiss national ID card to enter the UK from 1 October 2021 unless you:
have settled or pre-settled status under the EU Settlement Scheme
have applied to the EU Settlement Scheme but not yet received a decision
have an EU Settlement Scheme family permit
have a frontier worker permit
are an S2 Healthcare Visitor
are a Swiss national and have a Service Provider from Switzerland visa
What you need to know about crossing the UK border and visiting the UK.