I worked half a year in a hotel in Ireland a couple of years back. Most of the employees were british, as well as some various other nationalities, including a girl from sweden. I didn't have any problem speaking english all the time, that was the top reason I worked there(and to drink, of course). But there were times I was VERY glad to be able to speak norwegian to someone again. It was a way of clearing my head from all the english and feel a little closer to home, I guess.

I wouldn't like any law preventing this.