The whole argument about loss of sovereignty and democracy fails, as far as I'm concerned. I'm not even sure what people mean by loss of sovereignty. Canada, Australia and New Zealand are sovereign states, but their Head of Government is technically the Queen. The UK is a sovereign state, which can make its own laws. The EU has little practical influence and we can refuse to follow EU directives. Even if the UK weren't in the EU, we would have to comply with EU legislation if we wanted to trade with the EU, just as exporters have to comply with US regulations. Trading or dealing in any other way with different countries would be more complicated than one agreed set of rules.
The EU IS a democratic organisation. Arguably, it's more democratic than the UK, because MEPs are chosen by PR. In the UK, we've never held our MEPs to account, but that's or fault. I never understand why people vote for UKIP MEPs, because they know they don't take the job seriously. Their attendance is very low and they don't make much effort to improve issues from within or to represent their constituents' interests.
Democracy in the UK is becoming a sick joke. The FPTP system has always meant that many people aren't represented. I have never voted for the winning candidate in an election, so my voice has never effectively been heard. Not only that, the government is becoming the least transparent ever. Laws are changed without the consent of the electorate and the government uses 'statutory instruments' without having to go before Parliament for a debate and vote. If the courts decide the government has acted illegally, it's been known to change the law retrospectively - as it has done with some DWP decisions.
The Freedom of Information Act is being attacked. It is highly likely that people will have to pay for requests in future. In any case, an increasing number of requests are being refused. Public services which have been privatised, including some NHS services and academies/free schools, don't have to comply with the Act.
Another way that democracy is being undermined is that charities are no longer able to use their funds for lobbying. There are also currently plans to stop academics and scientists from publishing results if the government thinks they would damage their cause. This is particularly relevant with fracking. If researchers come up with clear evidence that fracking (or anything else) is damaging to the environment or humans, they are gagged from publishing and lobbying.
Sorry about the long post!! I feel very strongly that democracy in the UK is being undermined under our noses - and the EU has very little to do with it!