My son has begun classical guitar lessons(he's 8). I'd like to begin playing with him, and so I have begun shopping for a guitar for myself. However, I'm also interested in learning/playing folk style finger picking. The model I'm currently considering has a folk body, with a nut width of 1.8". Is it realistic to think that a folk style guitar can be used to play classical pieces(at an admittedly novice level), or should I commit to one style of play and respective guitar type (classical or folk)?
I commend you on your desire to learn to play with your son. That will go a long way towards encouraging him to stick with his lessons. Plus you will gain first hand knowledge about how much dedication and commitment are required to learn to play the guitar. And don't be too discouraged if your son advances faster than you do. Kids seem to have a greater ability to assimilate new information than adults.
You can certainly play classical pieces on a folk style guitar, but if you are a beginner, you might find a classical guitar with nylon strings easier to play and less painful on tender fingers.
As long as you stick with folk style finger picking, you would be able to do that on a classical style guitar with no problem. If later you decide to expand in to more chord based rhythm guitar featuring strumming with a pick, the classical guitar is not going to be ideal for that. But if later down the road you do decide to diversify your playing styles, perhaps you could buy a second guitar at that point.
But to your original question, yes you can play classical pieces on a folk body guitar - especially one with a wide 1.8" nut width. If you do chose to go that route, you might try "silk and steel" strings to minimize the pain on your fingers until you form callouses. They have padding (it's not real silk but polyester) under the windings which give them a softer feel. Less volume than regular bronze wound steel strings but at least as much volume as nylon strings.
Here is a link to see what I mean by "Silk and Steel" strings. Martin Silk and Steel Folk Guitar Strings
Have fun learning to play guitar with your son. That should be a rewarding experience for both of you.