Most "officers on the beat" don't carry guns, but perhaps as a sorry sign of the times it is not uncommon to see officers packing what appear to be quite heavy weapons (at least to my eyes) - e.g.:

https://i.dailymail.co.uk/i/pix/2015/04/26/11/22FFD9CC000005... https://qph.fs.quoracdn.net/main-qimg-0fe4637f8d1b1f981c7786...

You'll see them at busy places like stations, shopping centres, airports, busy public squares etc. At least in London - perhaps not so much elsewhere. I guess half of it is deterrent & reassurance, and the other half if to stop any "active shooter" type things before they happen.

There is also SO15 which are the sort of para-military dedicated anti-terror type people who don't patrol but are stationed around the place and use motorbikes to cut through traffic and down pedestrian areas, e.g.:

https://i.dailymail.co.uk/i/pix/2017/09/28/10/44C62468000005...

I think the main difference in the UK is, when the situation deteriorates enough to require police with guns turn up, the guns aren't there for show to try and subdue/persuade you. They'll usually shoot to kill from what I've seen/read/heard.