Yeah, some grounds over here are quite uneven like that because they serve as rugby grounds in the winter. My ground fielding has improved a lot this season, in previous years I've been pretty poor. Concentration is pretty important and also getting very low to the ground, nothing worse than having one roll straight under your hands.I don't drop catches but I misfield a lot. I find it very difficult to judge the bounce sometimes. May be because I play in the unrolled/rough outfields or maybe its just lack of concentration.
Just gotta get your entire body behind it then lad. Our outfield is dominated by two football pitches at either end. When the football season starts, it gets really cut up; couldn't tell you the number of hits I've taken to the knees, chest, chin etc.