There are different types of educational timetabling problems which are computationally difficult to solve. In this study, we deal with the High School Timetabling Problem which requires assignment of events, such as courses, and resources, such as classrooms, to time-slots under a set of different types of constraints. We describe an approach that hybridises an Evolutionary Algorithm variant and Simulated Annealing methods to solve this problem. This approach is tested over a set of real world instances obtained across different countries. The empirical results demonstrate the viability of the hybrid approach when compared to the previously proposed techniques.