Thanks Fernando and Johanna!
Yes I've just read Andreas' message so will probably give the cranberry juice a go as I won't be able to get hold of the GCG or chanca piandra herbs in time.
Cheers
Anne
P.S. Johanna, that link was to a site which is moving and they are selling their products at 20/30% off so I may order some of their chanca piandra anyway. Is it a reputable company? Don't most people get their herbs from Julia Chang? Thanks!