Im making a character who is trying to utilize shields. Will the skill level alone make a big difference? If so how much?

I hear an iron shield block 56% percent damage but they might have been a level 100 in block.

I never notice ANY difference in skill level myself, but the real differences come from the perks, which are only accessible through higher skill levels. Deflect Arrows, Elemental Proection, every Bash skill, and Block Runner are very useful.

The perks are the thing.

With those perks, a shield becomes a weapon in it's own right...a very effective weapon.

One has a 1 and a 0 in it, the other has a 2.