I think you'd be fine in a mix of quest green/blues with the odd drop.
On all of your toons and just starting heroics.

Let's say your group is Prot Pally x1 and Elem Shamans x4.
You have full dps on trash, and everyone has Lesser Healing Wave and Chain Heal on hotkeys.
When you need heals, your dps stops, but its fast and big healing done.

Conversely, if you go Prot Pally x1, Elem Shaman x3 and Resto Shaman x1.
You have less dps on trash, you still have Lesser Healing Wave and Chain Heal (everyone casts) emergency keys.
But you also have Earth Shield on the tank, for a lot of passive heals.
And you can 1x cast Lesser Healing Wave, Healing Wave and Riptide, for effective heals without stopping your dps.
When the content is challenging for your gear level, a resto makes things a lot easier.

But you can certainly get by without ever having a resto in the party.
4x Elemental is enough healing.

If you have the gold (and you should with one day of dailies)...
You can dual-spec one of the shammies.
So you have Elemental x4 and Elemental x3 + Resto x1.
On anything that is hard, change specs to Resto and make it a lot easier.
But on the trash or anything on farm, go full Elemental and win a lot sooner.

Prioritize gearing the tank.
A geared tank makes things a lot easier, much more so then anything else geared.

Heroics are basically Naxx10 challenge.
A few pieces of Naxx25, Ulduar10, Ulduar25, Toc10 or Toc25 level gear...
Can really help the tank trivialize content a lot sooner.