Key Post Class 2 is finished. You must opt to move to Class 3 by April 2027

[Threadser]

BTW if you have a log in for HMRC you can see the addresses that they have for you there. There's also links to change them. They store two addresses, your home address and your postal address, don't know when they would not be the same. It's in the Profile and Settings section

Thanks for that information. I will check out those addresses and see if they need to be ammended.