No. There are of course some armed units, but they don't do regular patrol work with their guns.

Armed units were involved here because the car Kaba was in was linked to a shooting the day before. Any involvement of firearms will invoke an armed response from police, however that does not mean they can simply shoot on sight and say they felt their life was threatened.

It hasn't changed. The proportion of police carrying firearms in England and Wales (Scotland and Northern Ireland operate separately, so E&W is the biggest UK data source) has held steady at about 5%. There are typically fewer than 10 total incidents in which the police actually fire a gun each year. Of course, it only takes one to result in a story like this one.

@Baketime

No it hasn't, but there are some police there with guns that are only supposed to be used as a last resort. Sounds like the shooter was one of those, but went a bit crazy:

by a Metropolitan Police firearms officer