I am looking for someone to write a retirement song for a teacher to the music of build me up buttercup thanks

You are asking someone here to write complete lyrics to that melody?

Those who know the teacher should write the song together.

A retirement song is full of personal sentiments and in jokes that pertain to that person only.
Have a glass of wine if you aren't alcoholic, relax, think of all the memories and funniest things you can about the person, and jot them down in any old order, not trying to set them to the song. Ask others for 2 each. THEN write the song.