We were told about this walk and found the start recently. The parking is very easy with a picnic area and toilets as well, good for any time of the year.
There is a walk either way, the river can be followed going up river towards Cenarth, it being possible to walk all the way there. The other way you can go to the Castle and do a circular walk through the town, there is a map showing this near the building.
We decided to go the Cenarth way, not all the way, following it for about a mile, then turning around and retracing our route. It was an easy very flat route and not too wet bearing in mind the amount of recent rain. The dogs both enjoyed it and it stayed dry as well, a bonus!
The walk follows the river passing old slate quarries with abandoned old buildings, there is a path along the walk that you can take up to the village.
We mapped on Wikiloc, this can be found at https://www.wikiloc.com/walking-trails/cilgerran-44559162.