Churchill admitted that he had a "reliance" on alcohol.

In 1953, he said:

"I am trying to cut down on alcohol. I have knocked off brandy and take Cointreau instead. I disliked whiskey at first. It was only when I was a subaltern in India,and there was a choice between dirty water and dirty water with some whiskey in it, that I got to like it. I have always, since that time, made a point of keeping in practice."

Many scholars have questioned whether he had a problem with alcohol. It's true that he was often seen with a brandy, but there is not a lot of evidence that it negatively impacted his life.

Good article on the subject:

https://winstonchurchill.hillsdale.edu/myth-churchill-alcohol/

Here's another article making the opposite argument.

Another good quote from Churchill:

“When I was younger I made it a rule never to take strong drink before lunch. It is now my rule never to do so before breakfast.”