I would suggest w2w pulling to learn, because you're not learning with smaller packs; you should try to get the feel of doing the 'norm' pulls the best you can. Worst case scenario, you wipe, and that is when you can adjust. If you don't wipe, then hey, you've got it down already. I'm very sure your healers will appreciate being able to do more than press one button, too.
If you're not that comfortable with being a tank yet, you can always queue up for the lower dungeons first before the higher leveled ones, or do PotD for a while to understand your mitigation tools as you get them starting from level 1 and head up from there; after that there's HoH. You can solo that so you don't feel the pressure from other players as well. Or Trusts, or what have you.
But I promise it's not that bad, and most players will be understanding that you're learning. There's horror stories of dickish players, but I believe they're more few than more.