I don't believe thinking up threats to make things difficult if, by some amazing occurrence, there was a split, is the right way to go. One benefits from friendship rather than animosity. (Especially to fellow Brits.) Scotland would be in enough mire without making things worse. And one can hardly criticise the appalling behaviour of the EU with regards to Brexit yet look to inflict similar on Scotland, should they ill-advisadly secede. One trusts these are academic questions only though as, as the previous referendum showed, the majority know it would make no sense, it's just a sizable minority that dream of cutting themselves off from the rest of the UK.