Welcome to SR cambridge, if you were not scared of going to an AA meeting you would be one of the very few who were not scared. Just keep in mind that EVERY single person in that meeting had thier first meeting as well.
If you are like me that fear is of the unknown!!! Try and get there a bit early, ask if you can help set up, you will make an instant friend!!
Just go in, grab a cup of coffee or tea (England may have both) and sit where ever you please, just keep an open mind and listen to things you can relate to. I am sure you will hear some one speak who has drank longer or more then you, but trust me, there will be every type of alcoholic you can imagine there, there will be folks who came close to drinking until the bitter end, there will be others who have quit long before things got really bad and every one in between. There will be folks who were binge drinkers and others that were daily drinkers, weekend warriors, beer, ale, cider, wine and hard liquor.
You do not have to say a thing if you do not want to, if you are called upon you can just say "I am new and just listening." You can introduce your self to the group if you like, you can say you are an alcoholic or not.
Keep in mind there are NO rules in AA.
Just step through the door, have a seat and listen, I promise you will not have to do a thing.