The percentage of people in Norway (as in Sweden and Denmark also) who speak English as a second language is amazingly high. You will be understood if/when you fall back into using English occasionally in normal life. Second plus: if you have already been learning the language at this early date (according to your plans), you are several steps ahead of others who don't even bother to do that when they go to Scandinavia.
It probably doesn't matter at all, but I'm a little curious about your 'European citizenship' remark, since Norway is currently not a member of the EU -- if that's what you meant by that. (What, otherwise, is 'European citizenship'?...). But, as noted, whatever that means is not going to matter very much in daily life; was just curious...