Preheat oven to 180 degrees C. Cook the pasta according to packet directions. Drain the tuna, place it into a medium sized casserole dish and break it into even sized pieces with a fork.
Cook the peas according to packet directions and set aside. Stir the soup into the tuna and add in the milk a little at a time.
Add peas, pasta and salt to tuna mixture and stir everything together. Bake in preheated oven for for 30 minutes.