I don't want to the terrorist's job any easier...but I have a plan...
why don't you dress up as Superman/ batman/ Captain America
(*delete as applicable) and sneak into a secure area, maybe Downing Street or Hoses of Parliment... carry a banner saying some activist rubbish...and a big bag on Anthrax...
....the public will help you as much as they can, maybe hold a door or two open for you...and the police will just look on in a disapproving manner...but don't worry...you'll get within an inch of your targets!
