You need to be VIP in order to fully play PvP. You'd also need to get to level cap in PvE if you want to join the 'free peoples'.
You can fight for Sauron for 'free', but your options are a bit limited.
Hoaving said that, I'm not VIP and don't do PvP, but from everything I hear, if it's PvP that you love, then LOTRO isn't for you.