Moving countries
Hello,
I would suggest you submit a support ticket:
support.guildwars2.com
‘Ask a Question’ located in top menu center.
This way you will get an official answer and have it documented should there be any issues.
Enjoy your travels. I love visiting new countries. 
If you try to log in from a location that isn’t already authorized for loggins then you will be sent an email to the address associated with the account asking you to authorize it. That email can be a bit slow to send. Once you authorize the access there shouldn’t be any issue.
As long as the country is in the same server park, you’re okay. For example, if you’re in Europe and move anywhere else in Europe you’ll be fine.
If you’re outside of Europe and move anywhere else outside of Europe you’ll be fine.
But if you’re in Europe and you’re moving outside Europe, or vice versa, you’re going to encounter a problem.
I cannot confirm this.
Last year I logged in from various places in Europe, the US and Australia due to travelling a lot for work.
At home I use VPN, using IPs from US and EU countries.
Never had a problem, outside of having to authorize the respective network (email link).
Based on my experiences, you will be 100% fine.
~ Whips ~ City Minigames ~ City Jumping Puzzles ~
As long as the country is in the same server park, you’re okay. For example, if you’re in Europe and move anywhere else in Europe you’ll be fine.
If you’re outside of Europe and move anywhere else outside of Europe you’ll be fine.
But if you’re in Europe and you’re moving outside Europe, or vice versa, you’re going to encounter a problem.
Not true. The region indicator for EU-server and NA-servers (rest of the world) are there to ensure you use the game for the first time in the region you bought it. But you have never been limited to EU or NA servers. I have a friend who is Canadian and always play on EU-servers. The reason is that he is originally from the UK and moved to the states several years ago. This way he can share time with his former schoolmates.
To answer the OP: All that will happen is that you will be locked out at first. You get an email with the request to click a link. Use that to authenticate that you are you and not a hacker. After that you can log in.
Keep in mind it sometimes takes several minutes (15 minutes max??) to recieve this email.
Arise, opressed of Tyria!