For those of you who have expressed an interest. I would like to draw your attention to the Gloucestershire Ale Trail web-site (http://www.glosaletrail.org.uk/). Apart from telling you where your nearest micro-brewery is, it also tells you where you can enjoy their beers!
Or, you can check out CAMRA’s initative of locAle. This accredits any pub that stocks beer that is brewed within a 25 mile radius. http://www.camra.org.uk/page.aspx?o=281521