I stopped "blocking" long ago. Blocks should actually be strikes IMHO. I replaced my "block" with a parry and have found gold in unbalancing uke by doing so.
In regard to doing atemi, just do it! you'll either capture their mind or break their nose, either way you'll realize the opportunity to execute technique and gain control where no opportunity may have existed before.
I uke for Dennis Hooker sensei down here in Orlando on a regular basis. I can tell you first hand (no pun intended) that even when you do protect yourself here, you still get hit on occasion. In other words , yes we do a lot of atemi!
Personally, I can't imagine even trying to execute a technique without it. There are times when demonstrating technique that the atemi is assumed and not really addessed, but remember, it's always there........
"Same Sword, Different Day" - Mongo