Slitherine

in the army lists you get ++ for impact troops dose this include heavy weapons lancers light spear and pike men.

No, it's just for troops specified in the list as "Impact Foot", such as Roman legionaries and some barbarian warbands. All of the other capabilities get POAs where listed in the combat mechanism.

"Impact Foot" is a capability, in the same way that the other capabilities you mention are. So, impact foot at impact with foot get ++. Heavy weapon, for example, gets + vs foot (so would be at a disadvantage vs impact foot.

You may be getting confused with "shock troops" which covers a number of capabilities (for examply, "impact foot" "pikemen", "lancers"). "shock troops" have a tendency to charge whether you want them to or not (if they fail a complex move test, they'll charge whether you want them to or not), and, unlike other troops will always be able to charge when disrupted. However, when you get to working out the POAs you use the capabilities.