C.P.
A lot of sandwich places will cater around there. Potbelly does catering and subway of course.
Gurnee probably has lots of places. I know Famous Dave's BBQ in Vernon Hills does a good job, but I don't know if they'll go as far as Lindenhurst.
I would just focus on what kind of food you want and call around. Even if they don't advertise for catering, a lot of places will do bulk orders for a reduced price.
Good luck and have fun!