http://www.worcesterbeerfest.org.uk/
14-16 August, Worcester (sort of in between Birmingham and Bristol)
I'll be there. Last year it was flooded off (it's on Worcester racecourse, by the river) but the year before it was great: over 150 beers plus ciders/perrys, food and live bands.
I may even go twice.
Worcester Beer and Cider Festival (CAMRA)