Educate an immigrant - Can't people get decked often in London?

What setting are you talking about?

In work/school, very rare past high school that anyone has physical alteraction, UK is a very passive aggressive culture in educated circles.

Now if you are talking about the biomass in the streets or the riff raff in some clubs/parties/pubs, yeah you are very likely to be attacked (think stabbing / bottled / acid attack). So I would advise to just mind which kind of environments you stay in

Don't start a fight in random locations, the number of people who carry some form of a weapon is high in the UK.
There are websites showing the likelihood of violent crimes and homicides and the UK is higher than "safer" countries.

Just look at what kind of people are running around the high streets... just avoid them. Live in safe neighborhoods with your own people.

While the police are relatively useless there, the slightest form of a disagreement may lead to most people calling the authorities. Due to the dense population in a small country the police usually show up quickly for these cases (i.e. verbal threats, aggressive stance, having an argument, ..).  Most civilians in Europe are only strong behind keyboards/on social media and in groups, most never did military service, don't know how to fight and aren't even that proud of their nations. They are afraid of anything and anyone and will (almost) never throw the first punch (especially the educated class). The less educated groups or people under the influence of alcohol/drugs may behave differently.

the outcome then is often:
1) both parties disperse and nothing is filed by the police
2) if it is more obvious who started the situation (ie CCTV, witnesses,..) the police may issue a caution
3) one/both sides get arrested, depending on what happened
Unless a serious crime was committed, it probably won't go to court. Especially not for "angry words with no witnesses that weren't threats".

A huge number of fights start in a parking lot or in traffic.

Crime in England is reaching new highs often, after a drop during the pandemic. There are strong anti-social tendencies in society which you will only realize after living there for a while. People are often trying to rip each other off with petty crime, break-ins, theft of car parts, or defrauding others through digital means. The culture has changed a lot.

We're not animals, we don't hit people. We use our words.

Lol no man unless u want to catch an assault charge