I have paid a few visits to my local Tesco Express, Littlehampton, over the last few days and they have Galaxy Mistletoe Kisses for 13p and Lindt Reindeers for 24p. I believe that is 75% off!
They seem to have quite a lot of stock too so other stores should have supplies. They are not with the sale bits but just on the regular sweet section so lots of people are missing them.
They also have the big Quality Street sweets for 9p each.
Apologies to those of you (like me) trying not to eat chocolate but I can't resist a bargain.