I found this
which is a summary of strike action in Creuse for last Friday. It impacts most public services. This
shows that 2 to 3 thousand people turned out in Guéret on Friday. Some interesting pictures.
If you use Twitter then perhaps follow @FBCreuse
(Radio France Bleu Creuse) which seems to give updates and has some video of the demo's in various parts of Creuse. Worth following to keep an eye on things or just look at their time-line via the link even it you don't Tweet.
I would think that outside of Paris anyway, motorways will be pretty much OK although you should plan for delays at tolls and through towns. Fill up before you leave the UK, make sure you have food, water and blankets in the car and I would say avoid Paris and other large cities (Rouen, Orleans and so on) if you can.
I expect Eurotunnel will be running, but check with them the day before. Currently their information page
We understand there may be industrial action in some areas of France, but can reassure you that Eurotunnel Le Shuttle does not foresee disruption on its service between Folkestone and Calais.
which is great but says nothing about getting back from Calais to Folkestone so that might need some extra thought and time.
Other trains including Eurostar, airports and ports are likely to be impacted.
handy page gives a list of strikes in France. You can also select by region or department.