I was in Superdrug today and made a purchase of £2. I was given a £1 off coupon on the next purchase of Oral-B brush heads. Currently, they have all Oral-B brush heads on 1/3 off in-store. So a further £1 off is a good deal I thought. Don't know what is the minimum purchase you have to make to get the coupon but I would assume it can be any value.