There's a vocal anti-EU minority in the UK, but it's still a minority. It just seems larger than it actually is because it's loud, and to some extent act as swing votes (the Conservatives want to avoid losing too many votes to UKIP, for fear of Labour beating them in the next election).
There's a vocal anti-EU minority in the UK, but it's still a minority.
That statement is true but potentially misleading.
In a poll earlier this month, as reported by the BBC[1], voting intentions if we had an in/out referendum immediately were 35% in, 32% out, 27% undecided, and 6% would not vote.
A different poll from back in December, mentioned in the same article, had a result of 32% in and 45% out, so it looks like the balance of opinion on this issue varies considerably over time, too.
(Both polls came from reputable sources, so I'm assuming that the sampling was done sensibly.)
In short, while it's true that the "anti-EU" group are a minority, the "pro-EU" group appear to be a minority of approximately the same size.