If you don't have much experience tanking, I'd start with a few 5-mans first to get your feet wet, and then move on to Naxx 10 once you start feeling comfortable. Gear-wise, however, you're definitely ready for Naxx/OS 10, and have enough survivability for 25 mans as well. If you have good healers, you can probably try offtanking Ulduar 10.
I think you're definitely ready for some Heroic action, and maybe try pug/guild some OS/Nax - but always go as OT for the moment (it's easier to learn the fights/work on your threat management). I would advise against running into Ulduar with that gear, OT or not.
For some advice, I'd change Glyph of Sunder to Glyph of Devastate (if you're using sunder, you're doing it wrong). Probably try to work on your avoidance stats, (in my opinion your threat stats are too high in comparison to your avoidance - not to say your threat stats are at where they should be either >.<). And I can't think of any reason why you've gotten two points into Imp. Charge - I'll send you over to Vene for the reasoning behind that: 7 Things I have learned about Specing - Warriors - TankingTips.com
Anyway best of luck, I'd say start raiding, but I think that you're a few epics short of going for Ulduar/ToC.
Ty for the replys i'm gonna take a look at TankingTips.com
The reason i have Glyph of Sunder Armor is AoE threat, the glyph works by using Devastate so 1 Devastate gives me 1 sunder on 2 targets, if you think i should change it to Glyph of Devastate i will try it
how do i find out if i have too much avoidance vs. threat and vice versa?
Personal experience, I would say. Ideally, you want to have decent threat stats amongst awesome avoidance, and then later on you develop alternate sets of gear - say one for pure threat generation, one for pure health, one for t8 4 set bonus even. Though at this stage I think you should be trying to establish just the one.
For aoe threat, I'd look more at glyph of cleave as opposed to glyph of sunder. Glyph of devastate is more for single target, and kinda a personal preference of mine , but it is very handy for getting sunders on.