Bethesda has announced it will release a Survival Mode for Skyrim Creation Club, and while it hasn't released just yet, you can opt into the Steam beta right now. It's an appealing mod if you're keen on punishment: it adds hunger, fatigue and weather-oriented survival systems, and you can't fast travel either.
But it looks like the mod itself won't be free. According to the announcement, "both PC and console players will get Survival Mode free for one week once it launches on their preferred platform." While no price is specified, it does imply that you won't be able to subject yourself to this punishing mod unless you fork out.
Still, assuming you don't mind paying what will probably end up being a small fee (and assuming you can overlook the fact that similar community-developed mods are probably available free of charge), it looks pretty good. The map is split into climate zones, all of which will require different levels of preparation to tackle. You won't be jumping into rivers willy nilly in Survival mode, because if the water's too cold it can kill you.
Meanwhile, health won't regenerate, and levelling up will require sleeping in a bed (so no mid-game health replenishments when you hit that next milestone). Carry weight has been "significantly reduced" which, to be honest, sounds like torture to me. But some people love to survive.
There's a whole lot of detail involved: head over here to read about every way Survival mode will make your playthrough a living hell. Creation Club will roll out imminently for Skyrim.