I didn't have any response from the forum request, but I contacted a student at the medical herbalism course in Lincoln and she recommended Waltham Herbs http://www.waltham-herbs.co.uk/
. She also said she would ask around locally and see if anyone came up with anything. I passed this on to the Lincoln Hotel.
Here is the elderflower recipe given to me by Sam Owen.
4 leaves of gelatine
Boil the elderflowers in water for 2-3 hours on a simmer. Take off the heat and leave to infuse overnight. Strain. Bring it back to the boil and add the sugar. Soften the gelatine and stir it in until dissolved. Remove from the heat and pour into moulds with berries and mint.
The taste was delightful - first you got the delicate flavour of the elderflowers, then the tartness of the redcurrants and finally the breath of mint. As I said before, it was one of the best desserts I'd had in a restaurant for a long time. All their food was amazing and I'm definitely going back if I get a chance to!
I'm sure you could use dried elderflowers for the infusion, but you would need to reduce the amount of elderflowers - probably to 1oz.
Talking of dandelion recipes, I got hold of an American book on dandelions by Brigitte Mars. It's out of print, but you can still get it through US booksellers. It is very easy to read, with a wealth of information. It has the most amazing set of dandelion recipes I've ever seen - everything from food to cosmetics. Jim MacDonald recommended it and I thoroughly endorse his recommendation.