Gary If needed, I'd keep a bloody spanner very handy, that fits the battery terminal so you can remove it PDQ
It could be anything, while the car is motionless one at a time, I'd try all the electrics, look out for traces of smoke, and mind you don't let the battery go dead. Isn't you're car still under warranty? If it is, send it back, last thing you
need is a loom fire while on a motorway.