My short answer is to not take the pack.
If you insist, it depends what kind of backpack. Other than perhaps a small, thin, ski-specific pack, I would not recommend carrying a pack for a beginner. Definitely don't take a regular hiking day pack.
A pack won't likely affect your skiing so much, but will make being on the lift more difficult and, perhaps, more dangerous, because it pushes you forward. It's one more thing to think about that isn't necessary.
I sometime carry a small Dakine ski pack with a hydration bladder, but usually only when I know I will need to carry my skis to hike somewhere, or if I want to carry more camera gear.
I would recommend carrying an energy bar or small snack in your pocket if you think you can't make it to lunch, and a small water bottle. Ski jackets generally have big inside pockets. You can always stop somewhere for water or a snack. Just dress appropriately for the weather, and be able to open zippers, etc. for when you get warm. Note also that, if it's cold, Camelbacks and the like tend to freeze up, so a water bottle is more useful.