But to do that, dont I need to undo the cap first? Or if I keep turning the housing it will eventually come off?
Yep you need to get the cap off first - the housing is just going round and round sandwiched between the block and the (probably immobile) centre bolt. So in that case, I'd say try an oil filter tool like this:
http://www.justoffbase.co.uk/Strap-Wrench-150mm-Sealey-AK6407 (as long as it'll fit through all the crap in the way like the steering arm :-/ )
As for the torque wrenches - good spot by dbug there.. and the bigger wrench will do you fine, it's a no-name but as long as it has a calibration cert it's probably as good as the next one, so to speak. (Speaking of torque wrenches - if you've not had one before, two things to remember: 1) always 'unwind' it to 0 after use and 2) don't drop it/use it as a hammer etc, they're sensitive things)