In reply to williemiller:
Recently I've always camped at Trevaylor Farm http://www.cornishcamping.co.uk/ .
I'd say it's a better site than the one at Sennen mentioned above (which I've also stayed at). It is, however under new management this year which I hope won't change things too much.
It's mid-way between Bosigran and the main south coast granite crags. Also don't forget the Killas slate at Kenidjack. Excellent at your grades. As for must do routes, follow the stars and you won't go far wrong.
Martin