What are the best ways to self-defence in London? England

Hi! I moved to London some time ago. Unfortunately, I was recently attacked by a group of young people in the center of London. It happened while the sun was still on.

There was no damage to my health, and the police report is submitted. I decided to not provoke them more, was quiet, so, no response to the mobs from my side. After a minute they left. Unfortunately, I couldn't run away because of my knee problems.

But I started to be seriously distressed about my safety. As I came not from the safest country, I always used to carry weapons with me. I know how to use them properly, and it gave me the sense of protection.

But here it's different. And I am still confused and stressed out about what I should do if it happens again. Internet tells some bullshit advices that would never work. And I can't run away because of my knees.

I would be grateful for advices on how to protect yourself in London