How do I play the chords in Rachmaninov's Prelude in C Sharp Minor?

I am a grade 3 player but like to dabble with challenging pieces. Just out of curiosity I bought the music for the Rachmaninov piece. I can play all the chords for the Largo section with both hands separately but together is proving difficult as the chords overlap. For example, right hand might be a C sharp octave whilst left hand is an E natural octave. Anyone got any suggestions how to play both hands? With some chords combinations I can't see the keys!