cant give you a route but head south/ south east for the nicest areas not north ( north is flat , dull and boring).
you want to head towards the saffron walden area for the best riding, look for places like heydon , gt chishill, arkesten to the west of safron walden and ashdon, hempstead, wimblish to the east of safron walden . try and make a route that includes some of these and you wont go too wrong.
if you can get there the best cafe by far is https://www.biciclettavelo.com/ in safron walden its ace. in fact i would plot a route that takes you there via the villages to the west of safron walden and then back via ashton, helions bumpstead ,castle camps , bartlow , linton, balsham, fulbourn etc