Heirloom gear for Holy?Follow

I have a lvl 20 pally that I have been play as prot. The other day a friend of mine rolled a warrior and asked me to change my pally over to holy and be his pocket healer. His idea is to lvl up almost completely in BGs. He purchased the plate heirloom gear along with the haste and pvp trinkets. I thought I would do the same, and not have to worry about gear too much. Problem is I could only find plate caster shoulders from the shard vendor. Is there not a chest piece for holy pallys? Am I stuck with wearing the leather/mail chest?

Also, the only healer I have played was a druid back in naxx/uld. What is some advise on pvp healing anyone could give me? Is Fol better than HL? Or vice versa?