The advice from the FCO is as follows:
Still current at: 02 December 2010
Updated: 29 November 2010
This advice has been reviewed and reissued with amendments to the Travel Summary and the Safety and Security – Local Travel – Punjab section (movement around Islamabad). The overall level of this advice has not changed; we advise against all travel to specific regions of Pakistan and against all but essential travel to other specific regions of Pakistan, including Lahore.”
I would certainly take legal advice before proceeding especially if you dont feel comfortable going.