I'll add my two penn'orth
No problem moving within the UK. I'm English and have lived in Scotland for 10 of my 40-odd years. I have yet to suffer any (non-sports related) abuse. Plenty of Scots, Welsh and Irish (both sides of the border) live and work in England. Inter-marriage, if it can be called that, is commonplace, with the children having little problem with 'who they are'.
Having said that there are certain tensions surrounding the media and the division of power - mainly due to England having 85% of the population (most of that in London and the South East). Independence parties are vocal and definitely have a say in how politics in Scotland and Wales is done. But, so far, there has been no vote for leaving the UK.
When it comes to sport, however, I'm going to need a thick, thick skin