Here's the thing. You, and you alone, have to KNOW you are ready. Everyone here could give you their spin on stuff that you need to have or don't really need. While that's all fine and good, it doesnt really encompass the whole question. Gear is only a fraction of tanking, and in my opinion, its the one you should worry the least about.
What you really need is knowledge, skill, and confidence. Without knowledge, you wont know what to do on a boss. If you had the knowledge but not the skill, you wouldnt be able to do what is needed. But most importantly the area where you, in all due respect as someone who has been there, Is confidence.
There are plenty of knowledge resources out there, Tankspot being one of them, and because you're here, ill assume you have the knowledge. Practice will get you the skill. You have to get the confidence. You have the gear. Do you have the confidence to walk in and say "stuffs dying tonight, because i said so"?
"Ive always wondered what we warriors say to make people attack harder, be healthier, or taunt mobs" -Orla