By now UNISON members who are part of Labour Link (the political fund that supports the Labour Party and fights to bring UNISON values and priorities into the Party) should have received their ballot form by post to their home addresses (and email if the union has a valid email address for you). You can only vote once! Since the security code can only be used once.
The ballot helpline is @ UNISON Direct - 0800 0857 857 if you require your ballot paper in a different format, or if you haven’t received one by now, they can help. There is also a textphone number 0800 0967 968 for members with hearing difficulties.
Outside London check out below my (John Gray) personal recommendations for other contested regional seats.