I don't know if there is a full list of UK potato days out there but this has a decent listing for next year.
Time to start getting enthused!!
If you have never been to one then I can recommend a visit - but wear elbow pads!!
http://www.potato-days.net/
I'm dithering about going to Ryton or up to Chesterfield to see Pumpkinlover again.. :-\
http://www.transitionchesterfield.org.uk/sites/default/files/potato%20day%202012.pdf
They have ordered twice as many potatoes this year after sellling out last!
Nice to see you if you head north saddad!