Shrek is a PC Statist and all PC Statists want BIG GOVERNMENT and this means higher taxes and more laws than anti-statist Libertarians.
All the English have to do is offer the Scotties a smaller government, with fewer laws and lower taxes. (And whatever tax cuts the Scotties get, so will the English.)
If they are silly enough to refuse, then they have been warned that the military option will be used.
I like to think that most Scotties are not really socialists and only pretend to be because they hate the English and wish to upset them and hurt their feelings.