We used this out of date Ordnance Survey Essex Walks Pathfinder guide book (published 2001!) so best to buy a more modern version https://shop.ordnancesurvey.co.uk/essex-pathfinder-walks-guidebook/
It took 53 minutes to drive from East London. You should be able to take the train to Audley End and join the walk there in less than 1 hour 20 but there are weekend maintenance closures at the moment.
The walk itself starts in the lovely historic market town of Saffron Walden. It soon passes some remarkable medieval Alms Houses and then Audley End House (see main picture) which was built by spectacular 17th century corruption but now run by English Heritage.
A lovely walk, not at all difficult apart from some not very well maintained stiles and there was some road noise from the M11 but that might have been since there was no breeze.
I will post and link other pictures here on Facebook.