Here's a very nice plan of a fast food restaurant... and if you don't think you'd ever need one, think again. I once wrote an adventure that centred around one, and even if the main action doesn't happen there, your characters do need to eat from time to time!
The layout is fairly conventional. Double doors to enter and a large seating area with tables and booths, some on a higher level, with a children's play area. The kitchen area is open to view behind the cashier's station where you place your order and pay. Behind the kitchen is the staff area with a couple of offices, a storeroom and the back door. (I think you normally need a staff break room and staff restrooms as well, but that may be a quirk of UK legislation...) There are customer restrooms and a drive-thru window as well.
There's a single-page overview and then a massive version that is battle-map scale which can either be printed out entire if you have access to that sort of print facility or paginated and stuck together if you are home printing. Before you print, you can choose between hex, squares or no grid at all and even eliminate the furniture if you so wish (perhaps it is an abandoned fast food restaurant!).