Might be worth phoning their helpline. I'm sure they will be obliging for a rescue. I'm sure it is because they sell 3 types and they are just cutting one of their list. Also not sure what the difference between regular lactol & lactol gold is?
ETA - I just phoned customer services. They said that it shouldn't be close to the sell-by. If you buy it and are unhappy with the use-by date, you can return it to any store for a full refund