Hi norwegian newbie, welcome to Surfing Waves,
The waves in Norway are probably like the waves that the east coast of England get (both being generated in the North Sea) so that means that the ideal board for Bali will not be the ideal board for Norway. Bali's waves pack much more of a punch and because these waves have more power you can get away with a smaller board with less length, width and thickness that a North Sea board. That said you will probably be able to find yourself a decent board to suit Norwegian conditions - just do not pick a toothpick out :D
That said, a 7'10'' mini-mal will be perfect for the waves you will be surfing at home and will be a great choice.
advise on where to find a good and cheap board around kuta beach
It's been a 5 years since I have been to Kuta but at that time there were quite a few surf shops selling boards - I would only imagine that number has only increased.
Hope you enjoy your trip - make sure you get some photos and send us some to post on the site.