Yeah we have some yahoos in Alaska that disagree with their having become a state (Sarah Palin's hubby was in such a group) and want to secede. There are also people in US territories like Puerto Rico which would like to petition for statehood. The last measure was narrowly defeated because many enjoy their exemption from US income taxes. The US like any large country has many regional flavors, customs, and even dialects though. But you also need to figure in the fact each state is quasi-sovereign in it's own right by design. I think what you are seeing in the UK may be something of an evolution towards that idea, where central governance is still in London, but each of the old lands that make up the UK will be semi autonomous. But admittedly my family's relationship with the Crown being a couple centuries removed I might well be a little ignorant on how things are broken up there
No, you're on the money! I understand that each US state has its own distinct micro-culture (and possibly at the country's geographical extremities this is more pronounced and possibly racially motivated too) and that in many ways individual states do already have a degree of legal autonomy. British visitors to your country are always advised that what may legal in one state is not necessarily so in another and to check. Certainly we crossed a few state lines when my family visited the US. There is much more of a move to separate Great Britain up into its constituent countries because Scotland - and to a much greater degree, Wales - believe that their cultural identites have become subsumed by "England" and "Englishness". In Wales there has been a decades-long struggle to get Wesh taught again in all Welsh schools and an upsurge in Welsh speakers. Scotland has had its own quite separate education system for a long time and it is still free for Scots to attend university. I have less issues with that kind of separatism, but the Scottish National Party (SNP) are quite a lot more agressive in seeking genuine autonomy from the rest of Great Britian, and at its extreme end, going into Scotland could become like moving from France to Germany on the continent. My concern is that this would work on a much larger landmass, but on an island that you can literally drive from one ened to the other in one day at its longest point and half a day at its shortest, it will not work at all.