I normally buy my shortcrust pastry!
I roll the pastry out over the plate. Then either cut the edges off with a knife or roll over the pastry with a rolling pin. Keep the excess pastry. I then put the sausage meat over the pastry and flatten it down. Then I put grated cheddar and mixed herbs on top. Roll out excess pastry again and cut into lattice strips and put on top. You can eggwash the top if you wish. Cook till the sausage meat is cooked at a medium temperature.