I'm a beginner pianist self-taught. I want to learn some classical music any idea's for a beginner song

your thoughts?

Hard to answer your question without knowing your level of accomplishment. I suggest you start with pieces from the Notebook of Anna Magdalena from J.S. Bach. Then try some of Clementis sonatinas followed by the easier Mozart piano sonatas. If you can get through that then you be ready for Beethoven.
Really depends on how well you read.

hot cross buns
i am a band teacher
i can play any instrument you throw at me
hot cross buns is the best begginer song for a pianist

If you're self taught, you definitely want to have a look at the Inventionens and Sinfoniens by J.S. Bach.

I linked the first Invention by Bach so give that a try.

You can benefit greatly from a classical fake book, which will contain hundreds of famous and not-so-famous pieces by all the well-known composers. A fake book gives you only a treble (right hand) score and chord symbols above the staff - no written bass or left hand notation. You can use these to learn some of the repertoire, they are simplified arrangements and easy to play.
Of course, you have to know chords to play them, but there is a lot of material on that.

If you read music, I'd suggest a childrens book - maybe Chopin - this gets you into the repertoire and you can progress at your own level.