Page 11 of the BRB, second paragraph:
"On rare occasions, a conflict will arise between a rule in this rulebook, and one printed in a Warhammer Armies book. Where this occurs, the rule printed in the Warhammer Armies book always takes precedence."
Also, Page 79 of the BRB, third plain paragraph under heading "Vanguard":
"Units that have made a Vanguard move cannot declare a charge in the first turn if their army goes first"
What does this mean to you?
Well, firstly, if Animosity does not place restrictions on the charge declaration then you are allowed to charge, as your Armybook will override the Rulebook and you will charge on your first turn.
An example of a stipulation which would keep you from charging would be:
Frenzy (pg 70)
"If, during the Charge sub-phase, [a unit] could declare a charge, it must do so".
If this unit had made a Vanguard, it could not make a charge move, because Vanguard specifically disallows charge declaration.
However, remember that you are only forbidden to charge if you take the first turn. If it is your first turn, but you have elected to go second, then you are allowed to charge as normal. The reasoning behind this decision is that you must give your opponent at least 1 turn to react to the positioning of your Vanguard troops, before you charge in (how unfair would it be to get charged before you could even move?!)