Just queue up, have some chocolate against the nerves, and just heal. I played on my friend's holy priest and though I understood jack all of what I was doing, I managed to heal the heroic just fine with no deaths that I can blame myself for anyway, so if I can, you certainly can with all that research! Go in there and do it!
Alternatively, if you'd feel safer, we can exchange realIDs if you're Alliance and we can use that crossrealm whatever feature, we can queue with some friends here, we'll be 85 too and geared, to let you get the feel of it, that'd be NP at all.
Drop me a message if you want to, or maybe someone else can do this?
Can get on TS too or whatever to make you feel comfortable. A friend of mine plays priest (as I mentioned), he can give you a hand too there. We're all very nice, so there'll be no pressure! (Edit: Of course I'd have to actually discuss this with said friends, heh, but yeah)