If you live in Scotland:

NHS Health Scotland invites people aged 50 to 74 across Scotland to undertake bowel screening every two years.

The Scottish Bowel Screening Centre will send a free home screening test kit (Faecal Immunochemical Test or FIT test) to your home address.

If the amount of blood found in your sample is above the normal screening limit, you’ll be referred for a colonoscopy.  In Colonoscopy the specialist uses a thin flexible tube (a colonoscope) with a tiny camera on the end to look inside your bowel and remove any small growths called polyps. They also use the colonoscope to check the bowel for cancer.

Further details can be found at https://www.nhsinform.scot/bowelscreening