audit table with permissions

I created functions and a trigger to audit tables on my database but I
have a problem with permissions on the functions and function schema I
created. I can grant permissions to the current user of the original
table being audited but I need a way to automate grants and revokes made
to the original table so that any time those change in the future I
don't have to worry about updating permissions or leaving a hole in
security by granting all users full permissions to the functions and
function schema.

From my understanding event triggers can't be set the grant/revoke only
create, alter or drop.

Any input would really help me, I'm very fresh to writing functions and
triggers.

Thanks,

Chris