EU referendum, brexit and the aftermath

Here:

https://www.hackney.gov.uk/european-election-2019

EU citizens will receive a form in the post, which they must complete and return to us in the pre-paid envelope by midnight on 7 May if they wish to vote in the European Elections in the UK.

If you haven't received this form by 20 April, please contact the Elections Office.

I haven't received it yet, but it doesn't sound as if there's any reason to panic if you live in Hackney. This may well be different elsewhere.