Sorry, I missed this in the signpost sticky. Hope it's not too late.
I can't move it so have started a new thread.
You will see a lot of France, that's for certain! It's very doable. I have done it, both camping and at other times staying in hotels.
Yes, you it's possible to ride 300 to 400 miles in a day, of course it is. Harder if you go all on the D roads, easier on N (mixed with D) roads and dead easy on motorways. I crack-on when riding and am lucky to average much over 40 mph on D roads, mixed with N roads, and not much over 60 mph on motorways. So you can do the maths. Harder though if you think that 100 miles in the UK is a long way.
Camping is fine. I do though think it slows your starts if you wait for the tent to dry from the inevitable overnight dew. Also, it's sometimes nice not to be fiddling around, day after day, in the dark putting up tent, cooking and washing your smalls.
Work out (I guess you have as you arrived at the three to four hundred a day number) how long you have got, how much slack (if any) you want to build in. You might also wonder why, to get to Spain (where I guess you want to spend some time) you want to do it by riding around France in a bloody big circle?
