Do you live in a town that has a Whole Foods store or an organic foods store? Most whole foods or organic foods stores will have vegan sections that carry things like Tofu Salad made with vegan mayo, or they'll sell products like Amy's. Not all of Amy's is vegan, but they have a selection of vegan frozen foods that are perfect for a lunch.
As for snacks there is always fruits (dried and fresh), nuts or trail mixes, fresh veggies like carrots, broccoli, peppers and don't forget grains! Cereal is a great snack - like Honey Nut Cheerios.
If you don't have a Whole Foods or an Organic foods store in your area, I'd look around your local grocery store and see what you can find. You'd be surprised at some of the things that don't have animal products in them - like most things pork (ex. Pork Stove Top Stuffing) because of it needing to be kosher.
It's a process, but if you take your time you'll be able to have filling and delicious lunches every day.