I visited Tintagel in late July and found that all the public toilets closed at around 5.30pm. I used a restaurant premises and the owner said that there was an issue regarding this that needs resolving. I just remembered that I promised I would send a comment in. There were still plenty of visitors around and what about coast walkers? So it's a thumbs down in that respect for Tintagel.
However, I noted that the facilities in Bossiney were available so good for them.