A new law is being enacted in the EU (this includes, in the UK) that will drastically limit availability of herbs, at least in the short term. EU legislation puts herbal medicine under threat | Business | DW.DE | 19.09.2010 Big Pharma Scores Big Win: Medicinal Herbs Will Disappear in EU Hundreds of herbal remedies now outlawed across Europe BBC News - New EU regulations on herbal medicines come into force

If you are planning on swaying within the next year or two, I strongly suggest buying your herbs now and just hanging onto them until you need them. The herbs will probably all be approved over time, but there is going to be a big bottleneck until they all are approved for use.