Lord in a Chariot is way too bad, you want him on a Dark Steed or a Dragon, those are your only two real choices.
This sort of thing is going to have a lot of problems in the long term with a number of matchups:
Dwarfs - S7 Bolt Throwers, Cannons
Empire - Cannons, Steam Tanks, War Alter, etc.
Daemons - Because they can get lots of S7 (though much of it is unreliable from spells, but the characters can/will have it). And because when you charge, their combo of Ward Saves w/ their Instability tests means your chariots can get bogged down and then stomped on by a counter charge.
Vampires -
VC will tarpit you, and again will counter charge and win by static res.
I'm not going to get into the rest, but
IMO I think that if you were building this for effectiveness you need to re-think it. If you're building it because you love you some mother F*@%!ing chariots, then go nuts.