Bowel screening, colonoscopy etc

I have just "failed" standard mass screening test (last one I would be eligible for at 74 i think) and have been offered a screening appointment and then probably a colonoscopy.

My previous colonoscopy was 4.5 years ago and "normal", not even any polyps. I do not score against any risk factors, except radiotherapy of the prostate 2 years ago, which seems to have gone well other than for late effects to my bowel movements. This makes for symptoms which could be bowel cancer. 

I am undecided about undergoing investigations. I would be unlikely to accept any treatment, but should I KNOW and adjust my life accordingly? 

Letter re "screening practitioner appointment" received at a weekend immediately before I go on holiday and I will not be in UK on date I have been given. I shall try to phone from overseas ASAP, but what shall I say?

Sorry, bit rambling, but it was unexpected and bad timing and has upset me more than prostate cancer diagnosis did.

Any and all comments, kind or harsh, welcome.

Thanks, dj.