I’m going to just come out with it: I work as a teaching assistant in France while JOINTLY working with a host-family as a live-in au pair. And I’m saving more money than I have in a long, long time.
(Just a side note: this post will only involve housing options and won't deal with student loans. I'll post a blog specifically for that in the near future! As for now, just know that deferring those little devils (student loans) is what I'd recommend doing before coming to teach in France. Definitely takes away some of that stress! Carry on!)
The thing is, in living with a host-family, my rent and meals are covered. Think about it: renting an apartment costs (ball-park) anywhere from 300€ to 600€ per month.
We make net 790€ per month.
Read: Not a lot left for café-hopping, flea-market-shopping, budget-airline-gallivanting, wine- and cheese-hoarding, and all that fun French stuff.
Another option to minimize your overall costs for living in France is to take advantage of the residences your school establishment offers. Monthly rent (that I’ve heard of) ranges anywhere from 0€ to 300€ per month, so it all varies. That, plus a near-non-existent work commute is pretty enticing. On the negative side, however, sometimes schools are located pretty far from the nearest city, so it can get to be somewhat boring after the novelty has worn off.
(Pro-Tip: the overwhelming bit of advice from past assistants is to live in the nearest big- or medium-sized city and commute to work from there. Anything under an hour and a half commute would be good for this! In other words, don’t choose a two- or three-hour commute just so you can live in a city. In that case, go for the student housing OR a cheap studio!)
If I’m personally comparing a host family to living in student residences provided by the school, however, I would much prefer the comforts + coziness of a host-family.