Prescriptions for more unusual medicines depend on your local primary care trust. We recently tried to get some probiotic drops on prescription but the GP couldn't do so as it's not on the approved list.
It works the same way as the infamous "postcode lottery" where in some regions you can get vital cancer drugs etc and in others you can't. Ask your GP to check whether the local PCT will permit prescriptions for Colief, but there's no point asking another GP at the same practice if the first one can't do it as they're simply not allowed to.
Good luck though, I hope you live in an area where you can get it.