Given what you said, it is pretty unlikely to be bowel cancer. Most likely, it is hemorrhoids or maybe a fissure though there are a whole load of other things it could be too - a polyp, ulcerative colitis, Crohn's, an infection.

Your doctor may simply examine you and if they find hemorrhoids or a fissure or anything like that, give you advice or treatment for it. They may ask you to do a FIT test, which is basically testing your stool to see if there is blood in it. If there is not, then the blood is almost certainly coming from somewhere external, like a cut near the edge or something. If it is positive, then that means it's coming from somewhere more internal and they may need to do further tests. Hemorrhoids are still a likely possibiltiy at this point as they can be both internal or external.

If the doctor has cause for concern, they might recommend a colonoscopy. However, as I assume you are well under 60, have no history of bowel cancer in the family and no symptoms apart from the blood and mucus, it is quite possible this won't be necessary. (Although of course, a colonoscopy does not only test for bowel cancer, so if they are concerned about something like ulcerative colitis, they might also do it, but it's far from certain.)

I'm no expert so can't say for sure what your GP will suggest, but those are some of the possibilities. You may not need any further tests or appointments. Your GP will know best.

Contacting a GP is never over-reacting. While it is unlikely to be anything serious, unlikely is not the same as impossible and apart from anything else, it's good to hear directly that a professional is not concerned. And on the off-chance that there is anything wrong, then the sooner it's dealt with the better.

Hope you get good news very soon.

Thank you so so much for such a lovely reassuring reply! My husband and mum both said ringing the doctors will be such a weight off my mind and will ensure if there is anything then it can be sorted.

thank you again! Really kind of you to reply! X