In 2007, there were plenty of people doing it so there was quite a demand for facilities. When I arrived at Dolgellau, the person in front of me got the last bed space and the last veggie hot meal. I tried to sleep in a crowded and noisy lounge, but had no luck, so took a series of power naps on the second day instead. I was perhaps just unlucky, as sleeping spaces became available later that night (just as I was leaving).
For start and end accommodation, the Travelodge at Severn View (Aust) Services is often used.