Information from UDC REGARDING NEW RULES ON POSTAL VOTE HANDLING
If you elect to vote by post, you cannot then go in person to the polling station to vote. You can however, hand your postal vote into the polling station or Uttlesford District Council offices if you have not posted it back. However, you must complete a Postal Vote Handling Form giving your name and address whether this is at the council offices or at a polling station. Without this, your ballot paper will be invalid and will be rejected. There is also a limit of 5 postal vote packs plus the electors’ own that can be returned by hand.
Political campaigners are also banned on handling postal votes, this includes candidates and their agents. Campaigners can only handle postal votes for close family members. Please refer to the briefing notes for political campaigners (PDF) on what is allowed. This must be either the polling station at which you would otherwise vote, or a polling station within the same electoral area, a maximum of 6 postal votes can be delivered by one person.
FROM THE UDC WEBSITE 01.03.24 https://www.uttlesford.gov.uk/article/6316/Voting-by-post