Taking the TUs to Court due to a possibly "unlawful" strike and the EU Comp payouts would be, er, interesting. There is some Research that would suggest that as a strike develops, both sides "dig in", - as long as they can afford the cost - and as they dig in, their attitudes to the other party harden, and their need to "win" becomes stronger.
So, a Court action might be a risk neither side wants to take.
But, being an idiot in IR terms is not unknown.