Indeed, there are plenty of public servers to practice or play casually on, however, you may find yourself trying to be recruited a lot, as regiments are always looking for new faces. If you want the Linebattle experience as well as the public casual play I recommend joining one of these regiments. If you're unsure about certain regiments you can check their Taleworlds page in the Battalions section of this forum.
Have fun!
Evan