The law lowers the likelihood that you will encounter a criminal with a firearm, it also lowers the likelihood that a criminal with a firearm would actually use it.
The statistics don't really back this up though, because if they did, the murder rate would have dropped when guns were banned, instead it carried on rising for another 5 years. Also, protecting me from a firearm, when the criminal just substitutes another weapon isn't really protecting me at all.
Also the public reaction to anyone with or suspected of having a firearm is far greater in this country than the US, and as such is far more likely to be reported.....not to mention that the law does protect you from criminals with weapons, we have armed response units withing our police forces and unlike joe public, they are actually trained to deal with such situations.
The police can only ever be a reactive force, that means there's always a time lag before they can get to you. In this country, we seem to have been stripped of our ability to protect ourselves (with a few exceptions, but they tend to require years of training to do well), on the expectation that the police will turn up and clear up your corpse afterwards, it's not really good enough.
Furthermore, this doesn't address the fundamental civil rights issue that the government has not made a valid, evidence based case for blanket firearms bans, instead relying on kneejerk responses to the very rare nutter to strip rights away from thousands of people who enjoyed a hobby in a perfectly law abiding manner.