then charged the knight. He then suffered 19 HPs and died before striking.... Did i miss something when I charged him? When a LoS charges does it tankshock/ram first then attack or do you have to declare a tankshock then hope to get in combat the next turn? etc etc...
It appears as though you may have, or the picture your painting is missing a few details.
For starters, I believe tank shocking/ramming is done during the movement phase. However I would not recommend ramming a knight, since you would likely be ramming its front armour (which while not the biggest issue since your ram would be a strength 9 hit, so would the blow coming back at you.)
So overall, I believe you'd have to hope to be in combat next turn.
As for when you charged the knight, first how on earth did you receive 19 hull points worth of damage!? What kind of knight was it? The knight warden aside, a knight would only be hitting you with three attacks and unless all of them hit and then he rolled 6's for the damage table you should have survived to attack back.
If your opponent had some good rolls, thats one thing, otherwise you should have been able to get hits in, and would have stood a good chance of bringing the knight down.
And keep in mind that against the knight, if your opponent didn't roll 6's on the damage table you get your daemon invulnerable save against the hits. (Note thats against the hits, not the hull points lost. If two attacks hit and each caused d3 hull points of damage you would only get two saves, not 2d3.)