I saw it, and have some advice. See if you can smooth out the continuity between the larger jumps. Some of the notes are printed smaller, and seem not to be part of the intended solo line; but I hear them being played on both the flute transcription and the organ prelude. The choral melody is in the left hand. I also found the 645 with singing:
Bach incorporated the melody from Cantata BWV 140. Here is a recording. Click on the watch on YouTube prompt:
Despite the stumbles, you handle the key of Eb well. It's not beyond your skill level; you'll rise to it and learn from it. You can ignore the slurs. That'll help smooth things out. And it might be worth listening to the flutetunes recording of the solo flute.
Tom