After some playing with Google Maps, I think I’ve managed to plot a rough outline of the route we’ll be taking on Sunday:

View Roman Circus walk in a larger map
If there’s nothing showing above, then click here to see it on Google.

It’s slightly approximated at points because it’s hard to follow footpaths on Google Maps, so the southern section (along the Roman River and through Friday Woods) shows up as basically a straight line when it’s anything but, but a look at Ordnance Survey maps on Streetmap will show you how many routes there are through there.