Um well there isnt really a best place to get iron at 27. But if you wanted for your level you can go to darkshire and farm the iron around there. You could go to vale but I think your pushing it then. Also 1k has a decent amount among with other minerals including tin and copper but you may be a tad two low. Also try stonetalon mountains.
by far the best place to get tons of iron is in the hammerfall are (arathi highlands i believe is the name)... there is iron just about everywhere in that zone. not sure if a lvl 27 can do it, but that is by far the best zone for iron.