Warrens Hall Nature Reserve

I tried something new today. I became concerned about the sky being blown out in some of my pictures and after a little reading up I decided to buy an ND filter.However the choice is not that easy, do you buy a normal ND filter or a graduated ND filter ?. In the end I opted for a normal ND filter instead of the graduated with a density of 0.9.Can anyone tell me if I have made the right or wrong choice please.