If you want to buy a house, you're going to need a lot of money, Norway is expensive. Secondly, Norway is a very hard place to be self-sustained.. I know some people who run farms (much like what you're thinking I guess, far from cities surrounded by mountains with a fresh supply of glacier water) and they have long since given up being self-sustained. It's a LOT of hard work and you cannot do it alone.
If you work you can run a farm as a second job of course, but living off of it is near impossible unless you join up with other people, get funding, and start a proper business. It really is idyllic during the summer months, but the summers are short so you'd be working long hours, and the winters are are long and too cold to grow anything.
Anyways, Norway is great for the most part. It's got beautiful nature, low crime rates, excellent social safety nets, high standard of living. Living here is great, but it's not the place to go for the kind of life you're describing.