Well, speaking of this semi-seriously, us Englanders are pretty fucked, we don't have guns, unless we're farmers or friendly with drug dealers (who aren't really the caring, sharing type, and bullets cost more money over here than in the US.)
I guess if zombies ever became a real thing, it'd start off with somebody saying they'd seen a zombie in the morning, and nobody would believe them, they'd laugh, ridicule and think they had dementia, had a serious mental illness, or were drugged-out on something major.
Then two people you know would say they'd seen a zombie in the afternoon, and you'd say "no shit!", thinking it was some kind of running joke, possibly from the net, like Epic Beard Man was last week.
By teatime, a lot of your friends and family would be saying "I heard my aunt said Uncle John saw some zombies, and one of them bit a man" and we'd get a bit afraid and stop for a bit in a haze of cynical fear (feeling all manly and skeptical and afraid) and by the time we actually realised zombies were here (ie. when it was on The News) we'd be so ill-prepared, we'd be motherfuckin' zombie fodder, anyway, the fuckers'd be everywhere!!!!
Many Brits would be eaten alive in cold flats in cold tower blocks, and would refuse to admit their death was that instantaneous, and would possibly remain extant after their guts had been gnawed, so used to proudly living a living death they can be.