Preheat the oven to 180ºc / Gas 4. Line a large deep baking tray with grease proof paper.
Put the margarine and sugar in a bowl and with an electric whisk mix until light and fluffy.
Add the oats, flour, salt and bicarbonate of soda to the mixture and mix until all combined.
Add half the mixture into the prepared baking tray, level out and press down with your fingertips or a back of a spoon. Spread the jam all over the top, sprinkle the remaining oat mixture over the top and press down.
Place in the oven and bake for 20-25 mins, until lightly browned. Leave in the dish to cool slightly, then cut into bite size chunks. Allow to cool and harden before removing from the baking tray and serve.