If you're considering Bishops Stortford, don't take a cab! It's £20 each way and at least 20 minutes. The Stansted Express (train) stops at Bishops Stortford and take 10 minutes plus around £7 return.
Bishops Stortford has a fairly standard British high-street with plenty of eating options. Impressive church in the town centre (St Michael's).
If the weather is rubbish and you want the lazy option, I'd take a taxi to The Ash pub which is basically around the other side of the airport perimeter in a small village called Burton End.
http://www.theashpub.com/. Above-average pub food and a very homely bar area to grab a pint and kill some time in cosy surroundings.
Hatfield Forest is lovely in good weather. On certain days/times there is also a small cafe open near the big lake to grab food and drink (outdoor seating only). I guess it's walkable, but negotiating the dual carriageways to leave the terminal area could be a bit difficult. I'd take the 42A bus 10 minutes from the terminal to Takeley village where it should be much easier to then walk.
http://www.firstgroup.com/essex/plan...or=8&source=sp