have you ridden anything round that way before?
there are quite a few decent mtb routes nearby but on the doorstep BUT they are all likely to be slop fest mud at this time of the year.
An easy one but without any tech would be to cycle to Carsington water, go round it and back again. The path round Carsington water is far from flat and has many ups and downs, would probably be a decent night ride from hartington but would include some road but likely very very quiet indeed. There’s a decent pub called the knockerdown just on the road out 😉
If you want to sample some proper peak district rocks then 30 minutes driving would get you to Wildboarclough free carpark at the bottom of Cumberland Brook. From there you could do an easy-up route on road for 3 (or 4) great descents around the area known as Macc Forest.
Let me know if I can help you further. The macc forest route isn’t really for novices or children I would say, espicially if attempting at night.
edit: for guaranteed smiles perfect for night riding, Cannock is an hour from Hartington.