Dual shell shotgun? or pump-action? Even the classic dual shell can make lay more damage than a regular handgun.
I guess the UK guys here all read the Daily Mail... Yes there is some crime in London (stabbings seem to be in vogue at the moment) but its like any other place in the the world. As long as you take some care in where you go and what you do you will be fine. Its no J-Burg or Bronx!
You're much more likely to get stabbed in Englnd than you are in Belgium, Greece, California and Iran, from what I ve seen since I ve lived in those places =p