The simple answer is yes, most laminate flooring can be used successfully in unheated buildings. In fact, today’s top brands are specifically warranted by manufacturers for use in just such situations. If a particular salesman won’t guarantee his product in your cottage, then look somewhere else. Not all laminates are the same.
The interesting thing about laminates is that they’re a rapidly evolving product. Improvement in the core material (it’s called high-density fiberboard) over the last five years has greatly improved moisture resistance. It’s now possible to use some laminates safely even in bathrooms, entrance areas and other potentially wet locations. But with this evolution there also comes a danger. Not all brands have kept up technologically. Cheap laminates are especially treacherous. They sometimes offer very poor resistance to scratching and wear, so be careful. It’s easy to spend too little on laminate flooring that are destined to disappoint.