Can’t drink moviprep

Hey all. Have a colonoscopy scheduled for tomorrow morning after a few symptoms and blood in stool found after FIT test. 
unfortunately the moviprep made me gag instantly and then vomit. I've always been the same with anything salty. 
Is there an alternative available in the uk to take as a tablet ? 
im not being overly fussy or anxious , its just a physical response i can't control. Gutted as was all ready to have the proceedure and get some answers.