Since I would like to be able to use the tent during the winter I was wondering whether I need to get a 4 season tent or whether I would be warm enough in a 3 season tent using a down sleeping bag and extra layers if required?
Hi Carl, although the season rating of a tent is similar to the rating used for sleeping bags, in the case of tents it is nothing to do with how warm they will keep you, but it's how strong the tent is.
Basically, a 4 season tent is sturdier and has less chance of being blown down and/or wrecked in strong mountain winds than a 3 season one, and should shed snow better, too. That's how I see it, anyway.
You'll probably find there is a bit of overlap between the two, with some manufacturers pushing their product a bit and giving it 4, while others err on the cautious side and give theirs a 3.
I'm not in a position to make any particular recommendations, but I predict most people here are going to suggest the Hilleberg Atko, which I understand to be the best lightweight one. If your budget won't stretch to that, there might be one or two 3 season rated tents that will take almost everything the weather throws at them.