Just to let you know I've moved your posts into one thread to make it easier to keep track of the questions and your replies
As @Strutt G
have pointed you toward, moving country is basically the same as moving out of the property in this case.
So, on 30 May you can fill out the 'home move' form in the app (in the main menu tap 'account' > under 'your property' you can tap 'move out' and fill in all the info it asks you for).
The team will then effectively move you out of the property - as you're moving country, don't worry about the forwarding address.
The FAQ you've been linked to for moving out has all the info you need about what to do if you'd like to know more
Hope that helps.