There aren't many free kids days out that are suitable for rainy days, Samlesbury Hall is my favourite. The parking is free and so is entry to the Hall. There are regular free tours which are hugely entertaining.
There is a small farm and a bee centre, both of which are well worth a visit.
The adventure playground is excellent, a firm favourite with both of my Littles.
I'm always impressed with the efforts the staff make to entertain youngsters. Today they have set up a hook a duck game in the fountain. Little Miss loved it.
They regularly offer free treasure hunts that are a great way to explore the Hall and grounds with little ones.
There was also a free story time but as is often the case, is was extremely busy so we gave it a miss. It's well worth getting there early if you hope to get close enough to hear.