I don't know anything about alternatives for the prep, but can give a bit of reassurance as I had a colonoscopy last summer when I was 40 and the consultant said the risk of bowel cancer at our age is pretty low and that I'd be "the unluckiest person in the world" if that turned out to be the explanation for my symptoms.

There are lots of things that can cause blood in the stools - hemorrhoids, a polyp, ulcerative colitis, Crohn's... I know this is limited reassurance and it's natural to fear that you might be the relatively rare person for whom it is cancer at a young age, but the odds are it is one of the many other options.

I will also say I didn't vomit when drinking the prep. Drink it slowly and take water in between.

Thank you that means so much xx 

I drank the pre scan prep with small amount of ice cold squash to try to mask the taste then had a long iced drink to wash it down, it must have worked as l had no problems with the scan. I would advise not to leave home once you have taken a dose. The recent meds were better than the ones I had about 6 years ago. unfortunately it's not in tablet form l agree it would be nicer to take. 
take care of yourself and try not to stress easier said than done. I find keeping busy helps.,l am going to the breast clinic on the 28 th so l understand how you are feeling and l would like it over soon so l can relax.

l hope you have a good outcome like mine and all is proved  benign.