i’m down in cornwall. the helston/penrose one is very nice, super scenic when you get up on the cliffs around porthleven. lovely lady, Yvonne, who runs it too.
i havnt done the lanhydrock one but i know people who have and its good too.
another option is a once a month 10k at godolphin.
if you do come down for the penrose one i recomend taking in porthleven after, its a lovely village with lots of galleries and down on the eastern side of the harbour you will find one of the best ice cream shops in cornwall ‘nauti but ice’