The current problem that a couple have with the law because they shot at a number of people who broke into their home should not be before the police or courts. The reason is very simple they are doing the same as the population of the UK would do if we were invaded by a second power. All of us would likely jump to defend our shores from the aggressors. Is there any difference between that and shooting at people who invade your home. In common sense no, but in reality and in the eyes of the law you cannot defend your home, so to take that to the extreme the British government could drag every person who defended the UK in front of the courts to face the same charges, rather than the way it would be celebrating the heroes that defended the UK.
We have the ability to defend our person, but that like the law above needs to be changed as you do not know who is holding a weapon or grabbing your bag, it might take longer than the time written into the law to sub-due or get your bag back. To me that is the same as defending your home. The people attacked or their home invaded should be protected from punishment for defending themselves or home not arrested and have finger prints, DNA and photo taken and then be worried about what the CPS will do.