Depends where you are going to in France. It will certainly be OK in the northwest. The further you get away from the UK the more likely you may have reception problems, especially with thick rain clouds in the sky, but in good weather you may be lucky relatively far south.
I have had reports these suitcase satellite units pick up most uk channels (not c5) as far south as 100 miles below Barcelona. But, as Lutz says blue sky is needed and of course pin point accuracy in setting up.
With a larger the dish it is more likely you will receive a better signal. Try the website below. There is some excellent advise on it.....mal