The vast majority of sailors from Scandinavia and Northern Europe who intend crossing the Atlantic outside the hurricane "season" generally make their way South in our summer months and from the end of September onwards tend to gather in places like Southern Portugal and the Canary Islands. One illustration of this is the ARC Rally which leaves the Canary Islands in late November. Very, very few of those boats are not South of about Lisbon by October.
There's good reason for this fact..
The proposed voyage from France in late January is of course possible but I would say you will almost invariably meet bad weather and if you do, you should expect it to be severe. I don't put too much faith in statistics, but some show the incidence of a severe gale (force 9+) off Cape Finisterre in July is 1 to 2 %. In January/February it is 17 to 20%. Once you are South of about Lisbon the weather tends to be slightly more benign, even in the winter. I type this in Southern Portugal at the moment, and in the past week a depression with winds of 50 knots + has run up the Portugese coast Northwards towards Biscay.
Can I suggest you make sure the skipper and crew of the yacht are experienced sailors and that the vessel itself is well maintained, before you agree to such a trip? It can be done, of that there's no doubt, and French ocean sailors are usually fine seamen, but as an old Cornish fisherman will tell you.
" Only fools and fishermen go west of the Lizard after September"..