Heat a large, heavy based saucepan and coat with low fat spray. Add the sliced leeks, cubed potatoes and bay leaf. Cook on medium heat for 5 minutes stirring occasionally.
Stir in the paprika to coat the leeks and potatoes, then add the stock. Bring to the boil then cover and simmer for 10 min, or until the vegetables are tender.
Remove the lid and add the milk and haddock for 4-5 minutes until the fish is just cooked. Meanwhile stir some of the soup into the mash potato until it is sloppy then pour back and the soup and mix gently.
Add the prawns, sweetcorn and half the chives. Heat through, then season. Divide between 4 bowls and garnish with remaining chives.