If you find it hard to sight-read it without mistakes, practice each part separately first, then combinations of two parts and three parts before putting everything together.
It is best to play every step and combination 3 times in a row correctly and fluently without hitting the wrong notes or making rhythmical hesitations.
Since this is the hymn from the 19th century, try to play everything legato except the repeated notes and notes leading to unisons (in the left hand) which should be shortened exactly by an eighth-note value.
Here is the file for listening and for printing.
After you complete the exercise, post your time to comments.