My current character uses a greatsword but I haven't been feeling the need to block too much but when I fight an enemy that uses two handed weapons they completely jack me up. Will boosting my block skill some help even if I'm not using a shield and how much of a boost will it give me?

Training up block with great sword will give you as good protection as blocking with shield. You can reach 85% damage reduction cap with a greatsword as easily as with a shield. Not only that, bashing with sword does more damage than bashing with shields.

Major drawback of having two-handed weapons is that in the early game you have lower armor rating. That extra 30 to 50 points of armor is a huge deal in the beginning. That disadvantage goes away as you level up, and your armor rating goes up. Another thing is that shield gives you extra slots for enchantments. And in my experience, you do not block arrows at all with greatswords, while shield blocks quite a bit of arrows, even without the block arrow perk.

I tried a two-handed warhammer build recently, and decided that I greatly prefer one-handed weapons over two-handed. I just didn't like the sluggish feel.

Look in the perk trees and your answer will be there.

I have a two handed Orc that is an absolute beast. Use two handed skyforge greatsword and battle axe. I also have Deadric armor, but prefer the skyforge weapons.
In response to your question, you can use the bash perks from block and max out your heavy armor perks < beware the level cap, you don't need to put all five into the first perk (name?) maybe only 2-3> but at a certian point, you will become amazed at how good your tank really is.
Yes you can block, also try to use your shouts to keep the 2h npc from jacking you up. It's takes a bit, but once your there, you are one man wrecking crew.
Have faith, you will get there.
Also what class are you? And don't forget about restoration magic, that helps a lot!

I think it will help quite a bit. Quick reflexes lets you avoid being hit, if you move of course. My greatsword wielder just went back to light armor, I found things got easier at the higher levels.

non-shield block perks with a 2-h weapon work great.

like said, keep in mind how you're going to reach max ac, since, overload equals wasted perks.

i'm playing an orc knight right now on a master DiD run that is a 2-h, block, enchanting, restore, stud.

I'm a Nord male using an orcish greatsword ( I like the way it looks) was using an ancient nord greatsword at first. I perfer to use light armor on my body and heavy on hands feet and head. I'm trying to stay away from using magic at all and only use potions that i find. I just really started using shouts and it's helping out but the only one I have is the one you start out with. I'm only level 10 right now.

You may want to stick to one or the other type of armor later in the game for that extra 25% perk. You can hit the cap with light armor just incase you
did not know. Are you using alchemy/smithing or enchanting? Very helpful those three are.
Be sure to use your nord "batte cry" ability, that has saved my butt a lot! Do you know where to get the locations of shouts? If not be sure to talk to those gents in the sky;)

Yeah a lot of times when I'm using a 2-hander I end up preferring light armor for the mobility.

I think a lot of people have issues with 2-handers because they want to charge in first thing and cut someone's head off with a power attack, rather then using the range of the 2-handers to use regular attacks, close distance, weapon bash, and then hit with a power attack.