Sounds like a great idea, I would just be worried about getting sucked into the habit of having them cater everyday, and end up blowing more money than I could afford. Regardless, it's great seeing problems like this solved (:
It was quite common to have this service during the internet bubble. Some folks put on a pound per month.
Also, there were similar services for keeping refrigerators stocked, soda machines, etc.
Most of the new people allegedly take an quite a few pounds.
Not worrying about what to get the team for lunch is a huge time saver.
It gives us more time to spend on users.
Disclaimer, we use ZeroCater twice a week and absolutely love them.