Well there is towing and there is towing.
First, make sure you are road legal before you set out, trailer lights working, number plate. Wrong cop on the wrong day! Speed limit in UK is 50mph, dont know about France, ask Slob.
Towing depends on the vehicle, practice makes perfect. You shouldnt have any bother with the Td4, it should be a pleasure to tow with. Just make sure you dont cut the corners too tight. Plus on full lock make sure the trailer clears the rear of the FL.
Then there is reversing

, I dont look back, too much neck strain, instead I use my mirrors. If you line the trailer up straight first or as close to the angle that you want to reverse, it makes life a lot easier.
Then watching in the mirrors, for example, if the trailer veers towards your left mirror then you turn the steering wheel to the left to correct. Small adjustments at a time otherwise you end up over correcting. Its confusing at first cause you think you should be turning the wheel the other way. If you mess it up, dont panic, just take her forward and get the reverse angle right, start again.
Is it a double axle trailer? these are more stable towing at speed, can require some effort when reversing, tend to get a bit of tyre scrub, as opposed to a single axle.
Reversing with a MOD ring and pin hitch, now thats another story.
Again practice makes perfect,