Given this is set in the UK, how accurate do you think they'll make the available weaponry? I'm guessing most of the weapons you get in the game will be looted from the police or armed forces. In the UK, legal civie weapons are non-automatic rifles and shotguns, and standard issue weaponry for armed police is augmented to semi-automatic.
"Oh I will, I'll shout if that happens, yes... something like... 'I WAS NOT EXPECTING THIS!'" The Doctor
I was curious about how they would get around that as well.
However, mix in the criminal element, small but will be packing varied levels of firearms, and the military, assuming they had time to be activated, there would be various corpses to pick through for supplies.