Please help me

A bit more than a year ago I got stopped and checked by the police I directly told them I had weed on me and was honest with who I am the out come was. As I have never had problems with the police they let me go and said they weren’t going to charge me but they said something about a anti drug course. I never received a letter Or anything and moved to another city a couple months later for a better job opportunity. Now in 2024 I live in another country and am afraid that one day in the future when I go back to the UK I will have problems. What should I do?