Should you take the plunge and I hope you do. I feel you will find driving in France a pleasure and not a hindrance. The motorway systems are very good with most only having 2 lanes of traffic, thus making it easier. No cars wzzing around you from all directions. You will also find once you are away from the port the traffic thins out dramatically. You may not see another vechile for miles. There are plenty of service staions on most motorways and in between these you will find picinic/toilet service areas.
Some juntions/roundabouts can be tricky but if you take your time you should be fine.
I have now lived in France for just over a year. Given the question would I rather drive in France or England. France would win hands down.