have received my RHS seeds last week, and just checked to see when i put my order in , it was the 5th December.
b&q! dont think they sell seeds of Kirengeshoma palmata somehow...
have you heard of the Hardy Plant Society seed swap?
if you collect some seed from your own garden and send it to them, they will in return send a comprhensive list too choose from, from memory it was about 20 packets you can receive for a nominal charge, and if you donate, you get an extra 10 choices. The range is as 'colourful' as the RHS, yet as you are relying on the other members to correctly identify the parent plant, there is the possibility of some surprises!
linette
www.applegategardens.com
www.toddingtonmanor.co.uk