Might be worth getting this moved to the Trip Planning section.
It a long while since I lived in East Northamptonshire so I don’t know what the current situation is. Bear in mind that there is now a depot at Kettering, with associated staff parking requirements.
Whatever you do, don’t try Corby where the council-run station car park is heavily oversubscribed. (Although there is now an arrangement with Tesco on the opposite side of the main road for ‘railway’ parking, for a fee.)