When you win a class say BN and you get £50 for first prize it means that you would only be able to win 2 classes before you were out of the class, so they give you notional money to go on his record instead - for BN £15, this means you can get all you DCs. You only get Notional money if you jump DC as well otherwise it is zero.
Now actual is the amount of money actually in your hand to take home and Notional Money is the amount that would go on Flints record.