haha! I used to live behind the retail park! I remember back in early 2010 when it flooded, we attempted to walk along the houses that back onto the fields where the canal is.... wish I had wellies. Town was like a massive pond and Writtle was severely flooded too.

Up towards Boreham there are a few nice walks near Mc'ds, but without driving it myself I couldn't tell you how to get there

In writtle there is a wonderful track near Writtle college cow watering campus which is about 1-2 miles long, which then goes onto more fields etc which is a lovely walk (only ever done part of it on my horse).... You can also connect it to the fields that the college own and walk along the footpaths there too. Newney green has a great pub too if your going that way!