Cut suitably shaped parts from styrene sheets and assemble into bench, etc...!
Sorry - couldn't resist! I have a number of older kits that contain similar "instructions" - although they are really more "guidelines" aren't they?
I think styrene is a good choice, as it is easy to cut, glue and file as needed. You can also bend it, so a bench/booth seat for a cafe could be a simple box, with one side extending above the "seat". Then bend the back slightly for a more comfortable sitting position.
If you want to do chairs, you might consider bending a frame from one or two lengths of wire, and then adding a styrene seat and back with CA. I have done this (in HO), but unfortunately have no pictures.
Tables could be as simple as a bit of styrene rod with a square or circle (cut with a hole punch) cemented to the top.
A different approach you might want to consider is filing or carving each piece from a solid block - this might work best for a bench, or a chair that is "slip-covered".
Good luck! And you should probably get a magnifier!
Andrew