I want to go fury for fast leveling, but don't know when to switch to prot so i can tank well in instances, ne1 know when a good level to switch would be?

You can tank instances right up to lvl 70 as arms or fury providing you know what you are doing and have a decent group.  Specialising in a specific tree is required for end game stuff to be honest more than levelling.  Basically you will struggle to do lvl 70/heroic instances unless protection.

when to switch to prot?
the answer is 70,coz once u got to prot,u are really slow grinding questing compare with arm/fury spec .( not talking about godly prot gear-ed warrior).so IMO stay arm/fury(dependz on ur weapon and ur habbits,then get prot when u reach max lvl,btw i found fury is a lil bit faster lvling than arm)
hope this can help u

If it didn't help him, it sure helped me. : )

Many thanks. Great to know.

i agree leveld from 15 to 29 in acoupl hours

start at lvl 60

1. Get Shield Specialization 5/5 From the PROTECTION table.

2. Get Improved Blood rage 2/2

3. Get Iron Will 3/5

If you really want to learn how to tank well, level a warrior as prot spec.  Its really not so bad considering that you can take a bunch of hits without having to bandage/eat, and once you get to lvl 40 you can get devistate + slow main hand weapon for some nice damage.

and what is iron will good for? Respec at 70, you can tank any normal instance til 70 and then just spec standard 8/5/48.