The Star Trek Conventions (Click to see the question please)

Me and my Boyfriend are wanting to go to a Star Trek Convention in London. However, we are having some troubles in finding the perfect one to go to. Our friends have tried to warn us off from going, explaining to us that the only people who go there are weirdos(needless to say, we don't agree (obviously)). If anyone can share any information to shed light on the 'situation for us' we would be grateful...
we are looking for prices, dates, location... and if you can - website Url would be awsome! thankyou ^.^