Use consulting and/or education when searching for a business code. If you can't find anything on the list that matches your description, use 999999.
Business codes are not used on your tax return at all - those are used for statistical purposes, so don't fret if you can't find a match. The code you enter won't affect the outcome of your tax return.
To see how to enter the code in Turbo Tax, click on this link, and choose your platform. The directions differ depending on your version.