Compost King
Free Ranging
I have forgotten to use grit for periods of time and the only thing that happened is that the hens laid less eggs. The grit just maximizes their nutritional intake however they will get enough nutrition to survive without grit. I wouldn't worry about a small period of time with no grit. Also if they free range they likely find their own grit, if you have a gravel driveway you can always pick out grit sized stones and throw them into their habitat and if they need it they will use it.