If you're craving some good sponge pudding, you could either:
1. Make some yourself.
Preparation: In small bowl mix 4 oz raisins, 2 oz currants, 3 oz dark brown sugar, and grated lemon zest for the filling. Sift 8 oz self-raising flour into large mixing bowl. Add 4 oz shredded suet* and a pinch of salt. Rub together to combine. Add a little milk. Cut through mixture with knife. Gradually add more milk until it comes together. Use your hands to combine into soft elastic dough. Add more milk if needed. Total amount of milk used should about 2 fl oz. Place dough on lightly floured surface. Roll into 8 x 12 rectangle. Evenly spread filling mixture over dough leaving 1/2 inch border. Brush border with a little cold water. Carefully roll up from narrow end. Soak clean cloth napkin in boiling water for a few minutes. Squeeze to remove excess water. Wrap roll in napkin twisting at each end and secure with string. Steam the pudding roll for 2 hours in a steamer. Wrap pudding suet roll in foil. Bake 400ºF for 1.5 hours. Unwrap. Cut into thick slices. Serve in warmed bowls with custard. Enjoy.
*Suet is a rich form of solid white beef fat that is usually derived from the fat surrounding beef kidneys. It's sold ready-grated and dusted with flour. Vegetarian alternatives are readily available, altho people who wish to avoid the hydrogenated vegetable oils from which they are made may like to try finely ground brazil nuts as a substitute.
Or you could:
2. Purchase a can of Heinz spotted dick sponge pudding.