That sounds like the route we took to get back to Rhyd dhu ninthace. The path isn’t well defined and although there are fingerposts, they’re quite far apart. It was a bit boggy when we walked it but easy enough to get around. The path also crosses an old slate quarry. Just found this site which describes the route -
https://sinclairdesign.com/blog/best-route-snowdonSomehow even the car park wasn't too busy at 7.30am on an early May bank holiday Monday! ( Although it was full when we arrived back). And we didn’t have to pay, we parked up just as a couple of men arrived back from going up for the sunrise so they gave us their ticket! There’s also a tea room and B&B in the village where we had a welcome ice cream, might that tempt you Mel!?
We stayed in a lovely cottage just outside Beddgelert.