Blythe Hill Fields has recently reopened it's new & improved quite large playground. It also has great views of London.

Jump on a bus & Crystal Palace Park has lots of fun Dinosaur displays for kids, (& lots of parrots).

Horniman Gardens has a small animal enclosure & the museum is free.

Ladywell Fileds has a skate park & a playground.

There's also Mayow Park, Dulwich/Sydenham Woods, Hilly Fields & One Tree Hill for more of a walk.

You're spoilt for choice really.