"Nut Brown" Ale is just a name for a brown ale. Sam Smith's may have coined it. It doesn't imply actual nuts are added.
I'd be careful adding anything weird like nuts, especially if you're a new brewer. For one, the nuts will have oils that will screw up the head of your beer. For another, it is a common mistake for new brewers to try to make wild beers. EG Blueberry Walnut cinnamon brown ale. When you can make the beers you like to *drink*, then you're in good shape. In my case, that's a good clean pale...heavy on the hops and with a pronounced hoppy finish.
I'm not saying experimentation with wacky brews is bad. But if you're new, you have no idea if you're making good beer or not really, since there's no frame of reference by which to compare wacky beer recipes. Lastly, your friends will be much more impressed if you make beer styles that are more familiar and make them well. That way you don't have to go "Isn't the spruce and the hint of licorice interesting??"