The United Kingdom is moving towards a fully digital immigration system, and physical visa stickers are being gradually phased out of use. More information:
Updates on the move to eVisas – GOV.UK
eVisas: access and use your online immigration status: Travel with your eVisa – GOV.UK
Entering the UK: Before you leave for the UK – GOV.UK
Apply for an EU Settlement Scheme travel permit to return to the UK – GOV.UK.
EU citizens in the UK and Brexit: what are your EU citizenship rights?
If you have questions feel free to ask the European Commission on their Facebook page @ECinUK – immigration lawyers contracted by the European Commission will answer your question.
More information on “Pre-Settled” and “Settled Status”: www.gov.uk/eusettledstatus
More information on your rights under the Withdrawal Agreement if ratified in the Commission’s questions and answers document at https://bit.ly/2LlcxeM