Yeah, what have you been feeding them? You should be feeding them a chick starter which I've only seen in crumbles.
If you've been feeding something else, I recommend getting a bag of chick crumbles asap because that would give them the nutrition they need to grow up strong and healthy. Feed that to them for the first 8 weeks. Then from week 8 to 16 or so feed them a grower ration. This also normally comes in crumble, at least here. At 16 weeks, buy layer pellets so they can get the calcium to lay eggs.
As for grit, if you are only feeding chick starter and no treats, it is not necessary. If they free range and have dirt available with rocks and pebbles and what not, grit is an option if you want.
Good luck!