A recent similar query (can't trace) concluded that public transport to Welwyn or Hertford, then taxi, was about the best solution. You can check possible routes on http://www.travelinesoutheast.org.uk, generally either National Express coach (==Greyhound) to Stevenage or Hatfield (can pay on day). or travel into North London and out again. There is a bus between Hertford and Welwyn via Tewin, so could be worth checking full journey, might fall lucky.

Edit sorry the traveline link hasn't been embedded, will have to cut n paste or search.

Thanks Wallbash and Penmere. The car would only be for getting to Tewin Bury and then to London. i'd return the car when I get to London. I don't even want to drive that much. Everything in the car is backwards!

Appreciate the info!!

You can get to Hertford East station by frequent trains from Stansted, changing at Broxbourne. A cab from there should be about £14 only. No need at all to go into London