travel from normandy to Loire Valley

As far as I know, the high speed train from Barcelona requires a change in Narbonne to get to Carcassonne and vice versa. Because of this change, I am not sure that it saves you a ton of time over a direct "regular" train. Whether or not your plan is reasonable depends on how long you have for the trip -- one week, then no. Where do you want to go in Dordogne and Normandy. IMO, getting around by mass transit is a pain in those areas. I spent 10 days in Paris and Rouen this past November. It was rainy in both places most days but a hooded waterproof jacket and boots were all I needed to be quite comfortable. In fact, I enjoyed the trip so much that I now plan to try to visit Paris every November.

Your proposed itinerary is feasible if you have enough time. With a car I should want at least 14 days (more would be better) not including Paris and Barcelona themselves (so maybe 23 days total).

If you have less time or do not want to drive at least as far as Toulouse or Carcasonne or Albi, consider trimming your plans so that you have enough time to enjoy some of these great destinations.

I think you'd catch the Barcelona train by taking the train to Perpignan and transferring.

The weather is really variable. Note however that daylight will be short and many sights will be on short hours.

You can plan out your train travel on www.capitainetrain.com. There is at least one direct train per day from Carcassonne to Barcelona and a couple with the connection in Narbonne and some with 2 connections -- Narbonne and Perpignan.

I do hope that you plan to have a car for most of the trip, such as to pick up in Caen and drop at Narbonne or Perpignan. Auto Europe is a good place to get a price quote. A sweater and a rain coat would be more flexible than a heavy coat, which you should not need. I would also carry a travel umbrella, as a cheap insurance policy.