How good is alteration at the higher levels, I mean is it worth perking it for a heavy armor dual wielding Nord?

I had something like this in mind for a build: http://skyrimcalculator.com/#23229

I'd use the ...flesh spells mainly at lower levels to protect myself
At higher levels it's more for the spell resistance (Magic Resistance and Atronach)

It's either Alteration or maybe Illusion, figured I'd try Alteration as I already have a character who frequently uses illusion.

It's gonna be either this or go with a 1hander and block, but all I keep reading is that 1h+block gets tedious after a while.

Any ideas/comments for this build?

My Breton is basically unkillable by any magic user due to the passives from the alteration tree and Atronach stone. With natural (naked) magic resist of 70 and magic absorption of 80, all spells effectively deal 6% damage.

Alternation spells on the other hand quite pointless for a warrior who should be hitting the armour cap without it's assistance.

Restoration spell with respite are the best spell set for warriors.

So I'd just level it up then, just perk for Magic Resistance?
I have a level 30ish 1h+block char, just perked it a bit wrong (first char) so I wanted to redo it.
Like, it has 3 points in Juggernaut, while 1 point is enough, 2 points in Alchemy, which isn't that bad considering, and 2 points in block.

If I'd play him, it'd be with blocking and up to Magic Resistance in Alteration, which would give me 80% spell block while blocking with a shield (I assume it stacks?)
Then it's just chosing between maces, axes or swords. I'm a fan of axes but I'm not sure how the bleed effect is, given the fact that I block half the time, the bleed damage could be good?

I agree with wtflag.

5 points in Alteration can be a good investment for any class needing the Magic Resistance. But any more than that doesn't make sense unless you're focused on spells and Magicka.