No, beer was never actually rationed.  However, there were frequent shortages due to increased demand (many women, for example, began to drink it for the first time) and interruptions to supply due to a lack of brewing materials and to German bombing, for example when Boddingtons' Strangeways Brewery in Manchester was hit in December 1940.

The strength of the beer declined steadily as the war progressed, but the price increased due to higher and higher taxes.  A pint of mild, the nation's favourite beer, cost 5d at the start of the war and a shilling (12d) when it ended.

If you are interested in reading more about life on the Home Front during the Second World War click here for details of how to visit the Department of Printed Books.

Source:
Brewing for victory by Brian Glover (pub. Lutterworth Press, Cambridge, 1995)