As of the local and Mayoral elections in May in England, you'll need to show photo ID at a polling station when you go to vote in person.
For Wales this also includes PCC elections and parliamentary seats.
If you don't have photo ID, you won't be given a ballot paper.
Here's a list of the accepted forms of photo ID that you need to take with you:
www.electoralcommission.org.uk/i-am-a/voter/voter-id/accepted-forms-photo-id
And if you don't have accepted photo ID you can apply online for a Voter Authority Certificate before 25 April and take that with you:
www.gov.uk/apply-for-photo-id-voter-authority-certificate