Every year the CAMRA (Campaign for Real Ale) holds a beer festival in Cambridge. I wasn't sure what to expect but found the atmosphere to be laid back and got to try Mead (honey based alcohol- traditionally given to newly wedded couple because it was believed that it increases fertility.
You buy a glass to use for the day but if you give it back when you leave, you will get your money back. Be ready for queues but its worth it. Make sure you have a DD and they get free drinks (not very common here!).
Last year they had 200 real ales, 80 ciders and perries, foreign beer, English wine, mead and cheese.
So get a group of you together and try the ales of England.