John C.
I can fully relate to what you have said.
I used to play Hammond organ - used lead sheets or just melody and made up the rest on the fly. In other words, I would say that I was a "Bar Room Organist".
After I retired we were in an RV park where they wanted to start a non-denominational chapel service. I had been entertaining in the park so they asked if I would be the organist for the services.
Since I had never played church music in my life and could not read 3 staff music, I promptly said no! Then I thought about it and said to myself "you dummy, here's a chance to learn something new - but - i'll do it my way, take it or leave it".
To make a long story short I faked my through the hymns - everyone liked the music and said "we've never heard those songs played that way and it puts a whole new spirit and spin on worship music". Mind you now, the music wasn't really changed but simply interpreted a little differently using more solo voices, less 6 or 8 finger chords that make everything sedate and muddy, and a little bass pedal rhythm and the use of some alternate chords.
I ended up as a full fledged church organist playing for over 6 years in the local Methodist church.
If I hadn't overcome the intimidation that I felt when first asked to do this, I would have missed some very important hours of musical enjoyment.
Walt