Britain will fall out of the EU on 12th April. The economy will crash and Tommy Robinson will be swept to power on a wave of nationalism. He'll lead the British army off to reclaim the empire and be killed near Gombe two months later as the army is crushed between Boko Haram and African Union troops.
Scotland will declare independence and rejoin the EU. Workers councils will spring up across northern England, and Northumbria, Yorkshire, Lancashire and Wales will declare themselves socialist republics. London will declare itself an independent city state and President Umunna will turn it into a tax haven for the super-rich having been refused membership of the EU. Rutland will declare itself a feudal dukedom.
The remains of the UK will endure a failing UKIP government so bad that the DUP proposes reunification with southern Ireland. Eventually a resurgent Lib Dems will gain power and a sad faced PM Clegg will sell the remaining state assets, including the Queen, to a cryrogenically frozen Rupert Murdoch for $4.2m.