With transparencies there is not much that is easy to do in mixed light situations. You can multiple expose using different filtration to correct each set of lights -- but that only works if you can completely control the lighting and turn off the other lights for the exposure the camera is filtered for. Or you can gel all of the lights to one standard color balance (in your case daylight). Neither solution sounds like it will be practical or economically sensible in your situation.

You can accept and learn to use the existing lighting as an aesthethic choice and abandon the idea of technical perfection (all lights balanced to one color range.

You can determine what the main two sources of lighting are (hopefully daylight and fluorescent) and make a split filtration decision and a bracket your filtration and exposures. If you are able it will be a good idea to test these combinations on 35mm first so you don't waste a lot of film

You can make your exposures and try to clean it up in Adobe Photoshop, This can be very, very time consuming and hence expensive (the high res scan will be the least of the cost here: time or skilled labor will be far and away the bulk of the expense).

Or you can shoot either NPL or NPS and have that scanned and have high quality Lightjet large format transparencies made of the cleaned up file.

provia 100F is an excellent choice. Ifthe bulk of the lighting in the place or at least the important bits are lit with tungsten, RTPII (64TII) will be a better choice.

A tricolor color meter (I like the Minolta Color Meter IIIF) is a necessary tool in these situations-- especially if you know how to use it and interpret its readings. It is actually very straight forward to use, but in mixed light situations you really have to think about what you want the final image to look like and filter the readings through your wetware.