Can't really talk about PvP
I can.
PvP can be broken down into 4 different types;
Imperial City (IC) - which is a mix of PvE and PvP elements, and lots of Close Quarters Combat
Cyrodiil - Open World PvP, AvA, One Versus Many, One Versus One, Siege and keep/town/resource/scroll capture
Dueling - 1v1, you can 1v1 anywhere even in areas outside of Cyrodiil
Battlegrounds - Requires Morrowind chapter to participate, 4v4v4 combat on instanced maps with different objectives.
It's important to note that Champion Points can be disabled for some PvP modes. Those modes without CP are more accessible for someone with lower CP.
For accessibility for endgame PvP, CP690 is preferred in CP enabled modes. No-CP does not matter what CP or level you are. As a newcomer, it's recommended that starting into a CP enabled campaign in Cyrodiil, you should be close to CP330.
Why do you need that much CP to participate in CP enabled objectives? The more CP you have, the more resources, buffs, max stats go up. A CP10 character fighting a CP690 character will be
grossly overwhelmed and unable to keep up with the player who has more CP. This is shouldn't be a point of frustration, as you can still group up with a 'PUG'(pick up group) or ZERG(24-man group) that'll protect you from other higher CP players. One of the best ways to start learning to play PvP is to go to Cyrodiil and join a group. Beware, Kyne is a lv50 and below campaign for Cyrodiil you can join to get your feet wet, without worrying about CP690 enemies.
So where PvP gets interesting, is character specs/gear load out. For Veteran Dungeons and Trials, which require specific gear/classes/CP set ups. Cyrodiil PvP is unique in that you build for self sustain/DPS/survival and/or build for group play. Which is
vastly different then how PvEr's gear up for end game PvE.
