at 65 you can go into UK on regular, so I'd go that route. With an 80 tank you should be ok. I'd dual spec the priest holy/shadow. Holy priest is pretty easy to box for heals. On my dps button my holy priest has a sequence, with mostly ,,,,,,,,,,,,,,,,renew,,,,,,,,,,,prayer of mending etc and that does the job for most trash pulls, and i just manually throw a big or small heal on the tank, and press a few aoe heal buttons. Hell probably with a dps warrior and priest, you probably wont need much if any healing for a while. I 'd suggest grinding the mage/lock/druid in UK until they hit 71, then take the 4 of them into AV until your priest hits 80, then just do the 3 of em. Just keep the warrior and priest near a summoning stone and do instances when you are tired of AV, or you need some more gear. I used a prot pally and a holy priest to grind up 3 locks from 70-80 using almost entirely instance grinding. I had all the blue caster gear by the time I was done.