1st point. You don't mean Wilby r'about at Wellingborough, do you? Yes, I agree this sort of behaviour is annoying and if the car cutting in caused an accident I think it would be possible to claim they were driving " without due care and attention".
2nd point. There is no law against using both lanes to queue into roadworks. Indeed, there are often signs to encourage it. The problem is 'us British' think it right and proper to queue (see what would happen in this situation in France, Italy etc!), but it is an offence to block the lane. It comes under "obstructing the highway". However, that doesn't stop me doing it in my truck as I find people who overtake annoying too, even though they are not breaking any law unless they 'cut in' as stated in point 1.