All eyes are on the UK, as Britons head to the polls on Thursday to decide whether they want to stay in the European Union, or leave.The UK is fiercely divided on the issue, with all living former British prime ministers, from both political parties, backing the 'Remain' campaign.But nearly half of the Conservative Party's MPs are backing the 'Leave' campaign, with Michael Gove, the secretary of state for justice, and Boris Johnson, the former London mayor, joining ranks with the far-right, anti-immigration party UKIP and its populist leader Nigel Farage.On the continent, the vote is being watched with much more concern, with fears that a 'leave' vote could deepen the crisis facing a continent already struggling with economic weakness, a refugee crisis and growing geopolitical instability.Apart from disrupting financial markets, a leave vote could bring far more dramatic change, along with many uncertainties.In this Al Jazeera special, Barnaby Phillips looks at the key issues surrounding Thursday's vote that could shape British-EU ties for generations.