I do this trip quite a lot from North Weald if I have nothing better planned - route up to Haverhill then come back down the M11 from Audley End (keeps me in practice dealing with Class D)
I would recommend going M25 J28 - Braintree - Gosfield Disused Airfield - Haverhill
Braintree and Haverhill stand out a mile, Gosfield is pretty obvious, but have a look on Google Maps to clarify, as are the 2 gliding sites.
Squawk 0013, Mode C or S and listen to Essex Radar, stay around 1300-1400ft, and admire the view. No need to actually talk to anyone until Cambridge.