warranty and applecare+ will only be valid in country of purchase, if you purchased it in uk or ireland then you would probably be able to purhcase applecare+ along with it, but then it would only be valid in those countries so experiencing issues would require you to travel there, if the device was purchased outside of uk / ireland then you would not be able to purchase apple care+ for it in those countries
you can get more clarification by reaching out to their official support channels
Get Support (apple.com)
And or
Contact - Official Apple Support
And or
Contact - How to Contact Us - Apple
Or
Genius Bar Reservation and Apple
Support Options - Apple