Walking anywhere around Kynance Cove, Mullion, The Lizard or Church Cove is wonderful. You could visit the Marconi Centre at Poldhu (check ahead for opening times though) and see his monument. Up nearer Land's End you could immerse yourself in prehistory by strolling to places such as Men-an-Tol and Chun hillfort/Chun Quoit. Lanyon Quoit is right by the roadside but is slightly disappointing in that it's been comprehensively and clumsily "restored." You could see a bit more recent history by visiting Ding Dong mine and you could take in the Nine Maidens stone circle while you're at it.

I've sent you a PM, Nick.