Mine turned out to be a partial and moved up and out of the way as my baby grew. The doctor should give you more details as to how severe/or not the positioning is. You will have more ultrasounds than normal to keep an eye on it. Also, there is a good chance that it will move out of the way by the time your baby is due. Mine was completely out of the way by the third trimester. Even when I had it, I was still walking, working, hiking and swimming. I was careful not to do anything like jogging or high-impact. The real drawback was the no sex.
I'm surprised the nurse said it would require a c-section as they don't know if it will move away as the baby gets bigger. My nurse/doctor's office sent me to an ultrasound specialist that had a better ultrasound machine to see exactly where the placenta was located and waited until they knew for sure before making any prognosis. I continued to visit the ultrasound specialist until they gave me the all clear. And again, I was told just to take it easy until they knew for sure and did not make predictions as to the outcome until much later on in the pregnancy.