We went to the Loire Valley twice years ago; once from Poland in an Audi Quattro Avant with two chocolate labradors in the back, and once from Yorkshire in a TVR Griffith 500 - fond memories of both trips. Make sure you visit Chenonceau and Chambord; the former is exquisite and beautiful, the latter is that again as well as epic in scale. Try and get to Chambord very first thing before the crowds arrive.
I went through this some time ago; a long trawl through t'internet found myself in the position that my specific ABS controller couldn't be repaired as 'the repairs weren't reliable' according to one chap who does fix others. In the end I bought a second hand one which put most of the lights out but it still needed to be coded along with something to do with the steering angle sensor re-calibration.
^^^They can as they sometimes have a higher voltage - I have always used the ‘connect the jump pack, leave a few minutes, turn the lights on, turn ignition on and start’ routine. Having the lights on mitigates a voltage spike to ecu’s.
The age old thing to do with immobilising a car is to remove the fuse for the fuel pump - no fuel injection car is going anywhere under its own power without fuel pumping from the tank.