So you wanna be a sorc healer? A noble pursuit, though certainly not for the faint of heart. ZOS knows that sorcs are not in the best place for healing right now, but fixes are not on the way until after the console release and next content patch. Fortunately, with some clever tactics, you can still do capably:

Starting with the easy; morph Grand Healing to Healing Springs for the mana regen. Also pick up the various sorc passives that increase magicka regen and reduce spell costs; the one thing we've got going for us is that we can fling spells all day erry day.

Try to pick up Negate Magic as an ult at some point, and take either of the morphs: one reduces damage to allies in the field, the other increases all regens and movement speed. If you can plant this at chokepoibts like inner keep breaches, you can greatly help your faction push through (and any enemies in the zone can't use skills, so they become much easier to squish).

If you don't mind doing a bit of dungeon delving, Undaunted has a few good healing skills. You can pick up blood altar immediately to be able to plant a regen AoE that allies can synergy to get a sizeable burst heal. Later in the line there's also an effective shield if you're with a group that hits the synergy key, which also grants them minor vitality to increase your other heals.

You might also consider a Major Sorcery buff to increase the magnitude of your heals -- one of the Surge morphs can provide this, or if you've got the Mages Guild upgraded there's an even better option called Entropy that also applies a DoT to an enemy. You can pop either before a fight or when you start noticing your heals are falling behind and you've got magicka to burn.

The only other thing you really need is something for healing spike damage. This is probably where you're worst off -- if your group won't hit blood altar's synergy, your best bet is probably the Blessing of Protection line for large groups, or the Healing Ward morph of Steadfast Ward when a single target is getting focused. Unlike a templar's breath of life, you'll have to spam a few times to get the target out of the red, but the good thing is both of these skills provide extra survivability to the target while you do your work.

If you find yourself being focused, don't be afraid to slot either Hardened Ward and Lightning Form on bar 2 for survivability, or Bolt Escape to get back behind the combat line of scrimmage. Mages actually make fairly survivable healers with all the tools they get.