ER Prot Hero. Might as well make use of it. The 3 skills in the main bar that you don't have access to can be replaced by those from the optionals you can get (Mend Ailment, Guardian, etc).
'Real' ele skills like nuke earth/fire elites are factions/nightfall, so you are left with Elemental Attunement for example if you want to make a different build.
Also, check the
Elementalist forum and in particular the stickies there for advice on elementalist builds.