Concept Design for Activity Cards

I have 12 sets of activity cards to design for education.
Each set of cards has around 20-25 double sided full colour cards
Size A6
Each set of card are held together by a keyring.
Looking for some concept ideas to make our set of products look like a range.
see website cosydirect.com for our logo and current style design.

Theme: Early Years. Rustic - but modern, natural, fun, simple,

Attached are some images of current swatches we have done, however we are looking for something different to this design wise. Layout wise it will be similar. Front cover/inside content.

Budget is set per swatch. There are 12 swatches to complete. All content will be provided.