It's not cruel to leave out her favourite food. She can still have them - just not every day.
Most children, given the choice, would fill up on Jammie Dodgers, Crunchie and Hula Hoops first - if you don't give her the choice, then if she's hungry she will eat the good stuff.
I would try leaving in the bread roll, carrots, strawberries and apple, leaving out the toffees completely, and giving EITHER the Hula Hoops, the Jammie Dodgers or the Crunchie - not all three. She's filling herself up on the rubbish rather than eating the good stuff, so cut down on the rubbish. Try introducing things like cherry tomatoes or chunks of melon or pineapple as well.
I know you're trying to be nice to her but it's causing her problems.