Battersea Beer Festival

This is a bit late and the event is no longer on (there's always next year), but that's not really the point.  The fact that its the Battersea Beer Festival is sort of irrelevant, it's great because CAMRA (Campaign for Real Ale) are amazing.  They put on loads of events like this all around the country all through the year.  The format is more or less the same everywhere: hundreds of British ales and ciders with a smattering of good foreign beers, mainly from small producers that take time over their products.