1) In a bowl, combine the yeast and warmed milk. Mix well and let sit for a couple of minutes until the yeast is foamy. Add the melted butter and sugar. Mix well.
2) Add the flour and salt. Mix well. Turn onto a lightly floured board or counter top and knead well for approximately 4-5 minutes. Put the dough in a generously buttered bowl and cover with a clean towel. Let rise for 1 hour.
3) Punch down and place the dough in a buttered 23-by-30cm bread pan. Cover and let rise for 30 minutes.
4) Preheat oven to 200C/Gas 6.
5) Place into oven and bake for approximately 45-55 minutes. Ovens vary so keep an eye on your bread. Tap on the bottom of your bread, if there's a hollow sound, it is completed. If not, bake a couple of minutes more.
6) Remove from oven, let the bread cool in the pan for 15-20 minutes, then remove and cool on a wire rack.
Fish and prawn sandwich:
1) Melt the butter in a frying pan over medium heat. Add the cucumber, carrots, celery, olives, lemon juice, lemon pepper, dill weed, parsley and salt to the pan and mix well. Let those ingredients simmer while you dice the fish and prawns into small pieces.
2) Add the fish and prawns to the pan, mix well and cover with a lid.
3) Place bread on each of four plates. Check the fish mixture and add the cheese. Turn off the heat and cover with the lid.
4) In a bowl, pour the lemon yoghurt. Add the fish mixture to the lemon yoghurt and mix well.
5) Scoop the fish mixture onto the bread to your desired fullness.
Serve immediately, while the fish is hot.