One of the first major advantages with us being in the EU is trade. The trading possibilities are greatly increased, with more countries and less available products only produced in certain countries. Trade with other EU countries will mean that some of the poorer countries like Bulgaria and Romania can become richer and their GDP will increase by selling their products to Britain, France and Germany.
However, there are some people who have to point out the problems with this. For instance, helping make some poorer countries a bit better off will increase their power and maybe overcome the rest of the EU and reduce Britain's power etc.
Another major advantage I think there is in joining the EU is that there is more help and support in making Europe a better greener place. There have been many talks around the world about “Global Warming” and how it is going to kill us all and being in the EU will give us a lot more power to help us prevent this. I'm sure we all want a much cleaner country and would all prefer to be greener but still there are some stupid MP's who have to point out some of the problems.
For example, being in the EU will maybe help us stay healthier and keep the planet happier but the EU maybe will not want to do it our way. They will encourage all the countries to do it the same way and maybe that is not how Britain wants to do it. (I personally think it's a great idea if we all do it the same way. That way immigrants will no what to do when they move to England.)
Crime: This is a major problem many off us have to cope with everyday. The EU can help us with this too. By removing the boarders any social services can cross the boarders and chase after the criminals etc with out having to go through customs. Therefore crime is more easily controlled and all forcers from different countries can be after the same criminal. (Obviously not the whole country's force!) It is also a lot easier to keep track of all the criminals on bale etc because there is just one extremely large database for all the criminals ever convicted in Europe.
This is easy to access from any police station with in the EU and therefore any police will no if any one has committed a crime served his sentence and done it again. And therefore will know to give him/her a worse sentence. However some annoying politicians wouldn't out that if there are no boarders the criminals can escape easily and if there is just one massive database it wouldn't be to hard for a hacker to hack into.
Immigration: A major problem in many countries and discussion that is never ending! This is the issue I have a problem with in the EU. I think it is unfair that Bulgarians and Romanians are coming over here and taking our jobs when we have the qualifications, went to university and everything; and they just thought they would have a stab at it and if they got it, and thought “what the hell” if they didn't. I suppose they do deserve to earn a living but it's still unfair. On the other hand we students have the right to go and study abroad without getting permission from the country so I guess it balances it out.
And finally, War: War has been a problem from the start of time. People arguing over land power and all sorts of things. But, being in the EU, we can get help from other counties (if they agree) to go to war. And another major point is that ever since the EU started (after WWII) there hasn't been a single conflict between any of the EU members which I think is a great step foreword to World Peace. However the one disadvantage of this is trust. If we trust other countries and then call a surprise attack we could be in great danger so there are still some problems with that.
To conclude, I think that Britain being in the EU is a good thing. All the things we can do over seas on the mainland. Study, work, etc. It's just great; make friends with different nationalities, eventually it will all add up to the one thing everyone wants.