Cheesy seafood bake

Name: Cheesy seafood bake
Ingredients: 300g medium potatoes (about 3), thinly sliced; 2 tbsp milk; 40g mature cheddar finely grated; 1 tsp rapeseed oil; 1 onion (160g), finely chopped; 1 red pepper deseeded and finely diced (270g); 2 tsp balsamic vinegar; 1 tsp vegetable bouillon powder; 400g can chopped tomatoes; ½ x 30g pack basil leaves picked and finely chopped; 1 garlic clove finely grated; 280g pack skinless cod loins; 100g frozen small Atlantic cooked prawns defrosted; 160g broccoli florets