Thank you! I'll look into it.

The Stansted Express does not run all night from Bishop's Stortford to the airport. If you park away from the airport, by whatever arrangement, you may need to find a taxi to take you there, which could wipe out any savings that you might make. There is also the added inconvenience and uncertainty and you would no doubt want peace of mind that you will have a reasonable change to making the flight on time. So I suggest you put up with the reliability of parking in the airport car parks.

Not sure how many are travelling in your party, but I'm going to be day tripping in a few weeks' time. With the early morning start and late night return I've decided to train it to the airport, and also to stay two nights (anyway I will be too knacked to drive home that night)

I have not costed a day's parking but the speed and convenience of train, compared with the high cost of fuel and Dartford tolls and parking tips the balance. Of course for a car full of people the balance tips back to using the car.