Expose yourself to the sounds of the language by listening to the radio and podcasts. Just having it on the background at work or when travelling is a great way to pick it up – especially with any simple dialogue like radio phoneins etc.
Memrise is good but tbh I found just getting out and listening and trying speak the language was far more effective. Plus loads of the phrases in Memrise seemed to be straight out of the 1970’s (though I was learning Swedish).
Don’t be afraid to make mistakes, trust the words that come to your mind. You have a huge advantage that your colleagues will understand English grammar better than you so when your Norsk grammar or vocabulary is out they’ll still get it.
Be warned though – if you meet someone and speak English with them, they’re likely to only ever speak English with you. The opposite is also true IME. I had lots of friends who I’d speak Swedish and they’re reply in English – must have sounded odd to passersby!
Motivation will determine how much you learn so be honest whether you’ll stick it or not.
Enjoy!