How old are the kids?
Rufford park is down the road, as is Thorsby Hall, Sherwood pines is too and has a go ape. Sherwood Forest to see the Major Oak (Robin Hood), White post farm, Sherwood Forest Farm Park, Southwell Minster, etc
If it rains there is a superbowl, cinema, water meadows swimming baths, indoor play areas in Mansfield. I think there is a learning centre type place where the brewery used to be next to water meadows.
Bit further afield, there are places like Hardwick Hall (decent pub food at the bottom of the hill) or come into Nottingham – nottingham castle, lace markets, caves, etc. There is also the ice arena, etc if required.
Crab & Mussle at Tuxford is a great seafood pub too that’s quite local, or a few nice locals in Wellow.
The national cycle network run either side of clumber too, if your out for riding.
I grew up for 18 years down the road in Mansfield Woodhouse, Before travelling away with Uni & work for years, back in Nottingham now though. Drop me an email though if you need any further info