No, Helm's Deep wasn't F2P because of Epic Battles
You are corect and I mispoke. The Epic quest line was totally free up to Helm's Deep and then was Free again after Helm's Deep but you could actually skip the Helm's Deep part if you wanted to.
If you wished to do the parts of the Epic that existed within the Helm's Deep expansion you needed to buy it.
Originally Posted by Elmagor
Every epic quests after ring destroying needs some questpack/expansion
There's NO Epic Quest line after you reach Mordor, that IS the end of the Epic Quest line. Once you reach Mordor the Black Book quest line starts and is totally separate from the previous Epic quest line.