Some doctors suck, no matter what country you're in. I've heard similar stories from people in the US, India, everywhere. You have a right to a second opinion in the UK - use it if you're unsure.
https://www.nhs.uk/be-clear-on-cancer/symptoms/bowel-cancer
> If you've had blood in your poo or looser poo for the last three weeks, tell your doctor. Chances are it's nothing serious, but you're not wasting anyone's time by getting it checked out. Call your GP today.
https://www.gov.uk/government/news/government-launches-its-f...
Three months is reasonable number if you have no GP (have to register first), bad english and live in poor neighbourhood.
Visiting foreign doctors is cheaper and faster.