Firstly, Europsceptism alert! The free movement of all people in the union would inherently lead to the influx of poor people from Romania and Albania to come into the United Kingdom. Material conditions for them won't get better, and they'll simply use jobs that the British government has created for the British people. Because of this, the British public is left with a feeling of being wronged by seeing their jobs being taken by Romanians and Albanians. Apart from this, many Albanians and Romanians would just have more children in order to claim British benefits; that's right, British tax-payer money!
Secondly, many schools around the UK now have classes filled with Muslims and Southern Slavs, most of whom can't speak English. This is a cultural issue; the Southern Slavs whom can't speak English will just make the British government hire more Southern Slav speakers, therefore destroying the institutions of the English language. As for Muslims, these people want to turn Britain into sharia; keep in mind that many of these Muslims are second generation migrants, whose parents escaped from the system that wish to implement.