Three points is the minimum and that will be applicable if you are offered and accept a fixed penalty, or if you go to court, plead guilty and there are no aggravating circumstances.
I did the other week, went through a red at 16mph following a bus. I accepted their offer, 3 points and �60.00 fine paid within 28 days from notice. If you dispute claim, chances are you could get more points and bigger fine if it dispute fails!