You'll need ID when you next go to vote, or else...
To vote in local elections, it's no longer enough just to walk into your local polling station. Here's our cheatsheet so you don't lose your vote
As well as a passport or driver's license there are a number of other forms of ID which will be acceptable at polling stations. Here's a full list from the Electoral Commission: Types of ID which will be valid at polling stations.
If you don't have ID, you have three options: