The answer to this question has to be 'yes and no'.
If you were to enter into a civil partnership, with another woman, while still married to your husband, you could be prosecuted for contravening the provisions of the Civil Partnership Act 2004. Such a prosecution would be separate from the charge of bigamy which (in the case of marriage) is made under the Offences Against the Person Act 1861 and the word 'bigamy' would not be used in the indictment.
The first such case was committed for trial just over a week ago:
http://business.timesonline.co.uk/tol/business /law/article1832235.ece
Chris