Welcome to the forums newtothehobby,
If you are wanting to build a town with usable interierors try both villiage works and thoumonts (or the harbormaster) together. Villiageworks is used to "flesh out" your town with several quick flats (the unimportant buildings your characters don't go into) and, like LD mentioned, you can add interiors to some of them by printing mirror copies. Another option is to use interiorworks pubs and inns to flesh out the buildings.
For variety you can use some walls (interior or exterior) from thoumonts (and/or the horbormaster) to change up the VW houses. You can also use the set by itself to make a few houses by changing the footprint/layout. You can also build your key buildings like this.
Don't add interiors to all the buildings right away, just do a few random (or not so random) ones plus your key buildings. Then as you get more sets (like pubs and inns) you can add interiors to the unfinished buildings so they are not all carbon copies. If the players try to enter one of the flats let them and say they find nothing of interest (the same thing you do when you design your own city or setting, flesh it out as you go).
Depending on how much you want to spend on this project (in time and money)
get... Villiageworks + Thoumonts
Then maybe + Harbormaster or Pubs and Inns
Option 2... wait around for Denny to finish *twitch* himmel, *twitch*twitch*... ... oh hell you'll figure it out
Richard