I think we have the spanish slug the arion vulgaris, as every morning around the hen food are huge fat slugs gorging themselves on the hen food.
Watching BBC news this morning was a report that this cannibal slug has now moved to the UK. The plus side of having it is that it is food for hedgehogs which I know we have, the downside is of course the problem for the vegetable patch. If they are a nuisance the best way to get rid of them is fill a pail with water and drop them in apparently. I have given the link to an article about them.
(Arion vulgaris) which has become a problem in northern mainland Europe in recent years, and has been nicknamed the 'killer slug' for its cannibalistic tendencies.
http://www.bbsrc.ac.uk/news/food-security/2013/130103-f-slug-which-could-threaten-uk-crops.aspx
