In their 2007 pre-budget report Delloite are saying that biobutanol will soon benefit from an excise reduction:
The Chancellor proposes to reduce the excise duty on biobutanol from 50.35 to 30.35 pence per litre. The reduction will apply to biobutanol used as a road fuel in specific pilot projects to be individually approved by HM Revenue & Customs. The measure will take effect 21 days after the associated statutory instrument is laid before Parliament.
No doubt BP are very happy to hear this as they are soon to market biobutanol blended fuel to motorists in the UK (previous post).
This TimesOnline article, while a little old, has more information on biobutanol and biofuel use in the UK.