Grmpf, what stuff are you playing... Ok, you don't need perfect pitch for this. The key is C major, I hope you figured that out. If not then you know it now. Apart from one place you need only these four chords C, G, a, and F. They actually appear in this order. If you don't know what chords are:C: C - E - GG: G - B - Da: A - C - EF: F - A - CYou can distribute the notes of each chord between your hands. Play around a bit to find out what sounds reasonable.Now, first get the chord progression right by playing along with this masterwork. Don't think about the melody yet. At 0:46 on the word "angels" you need an additional e chord (E - G - B). All of this shouldn't be that hard. Then you can add the melody. For a melody your first choice always are the notes of the chord you're playing at the same time, that's why you have to know them before. The piano melody starts g - e - c - d, where the first three notes come from the C chord and the last from the G chord that follows. The melody goes on d - c - g - e - d - c. Again, the remainder shouldn't be that difficult. If you don't get the melody perfectly right, find sth. similar that works with the chords - nobody will realize it.