yeah, shadows over europe still tout how hard it is to run and be armed up. one of the commentators quips about keeping a low profile with weapons stating how different it is to the states.
i'm not hardcore on lore but it wouldn't make sense for everyone in the uk to start owning firearms.
stuff like holdouts and light pistols are still available in the underworld, but you'll find because of the low prevalance of firearms, the police and gangers won't be geared up for it. t
they'll favour impact armour over ballistic and tend to carry non-lethal weapons (police) or melee weapons (gangs). there is obviously the firearms division of the met, but they've got a response time that varies on where you are in the city. lieutenants of gangs may well carry a gun, but it wont be an ares alpha!
eastern europe is a different kettle of fish. if you end up in their, the police are armed and the gangs will be, but i can't promise you'll be over there anytime soon so i wouldn't build for it.