Thanks for the advice.
I went from the Adur Centre along the West of the river until I reached Ricardo, turned right to reach the Toll Bridge. The river path to the left had signs about it being closed at Cuckoo Corner, so I crossed the Toll Bridge and followed the grassy muddy trail directly...
...I could just run along the coast towards Brighton on the road and then come back, but along the river feels like it would be more fun. I can wear trail shoes to deal with any mud.
I'm a bit lost. If you click on my link in the opening post, you'll see my proposed route - up one side, over a bridge and back down the other side.
I think you're suggesting this isnt possible, but I'm not sure quite where/how/why!
1. Is it possible to go north along the west bank of the Adur, ie go around the airport and under the A27 etc?
2. Is the South Downs Way the only place to cross over the Adur?
3. What's it likely to be underfoot along there currently?
(I need to take my son to the AC to go climbing so...