Fascinating place Cornwall, been there many times over the years.
A lot of our history was made there.
Tintagel is the small village on the mainland, whereas the castle is on a rock, now with an aerial walkway between them, due to erosion over the years by the Atlantic. Must admit I did chicken out of crossing the bridge, I suffer from terrible vertigo, so never been to the castle itself.
The river is called the Camel, now whether it got its name from Camelot or the other way round it's not clear.
The small village/town of Camelford is also in the running as the site of Camelot. There is a Celtic cross here so that again indicates some connection with Scotland.
The cliff top walk along the coast from Tintagel to Boscastle (scene of the 2004 floods and devastation) there is Bossiney Mound where Sir Francis Drake was elected to Parliament.
The whole area seems to be a mixture of Welsh and Normandy.
I supose the round table could have been taken by the Celtic clan to Scotland by sea up the west coast.
All very mysterious.
A good site here for information of the area.
http://www.tintagelweb.co.uk/home.htm
Also go to the English Heritage site.
www.english-heritage.org.uk
Hope this help you in your search.
Tornado