What to grow now?

[Ferret]

I'm planning my planting for next year and one thing I am determined to do is have a medicinal garden. I'm married to that rare breed - a medic who is interested in herbal medicine. Much of our modern medicine cabinet owes its existence to herbal medicine and if and when THSHTF I don't want the battle to be lost for the lack of a horse.

Where do I start - what would you consider to be essential plants, and good to have plants? We already have most culinary herbs, comfrey, feverfew and have access to a large number of wild plants.