Preheat the oven to 150ºC/300ºF/gas 2. Grease and line a rectangular cake tin (roughly 20cm x 30cm).
Place the butter, sugar, honey and salt in a medium pan over a low heat, then allow the butter to melt, stirring occasionally. Meanwhile, roughly chop the nuts and any larger dried fruit, then stir them into the pan along with the oats.
Transfer the mixture to the prepared tin, smoothing it out into an even layer. Place in the hot oven for 35 to 40 minutes, or until golden around the edges. Leave to cool completely, then cut into squares and serve.