Even in that case, Apple could withdraw from the market.
If push comes to shove and apple actually called their bluff and withdrew completely from the UK market, I'd bet that that government would become so unpopular that they would not be elected again for quite some time.
Governments are extremely powerful. They may issue a gag order (https://en.wikipedia.org/wiki/Gag_order) that makes it illegal for Apple to do that.