Bodmin & Wenford Railway, Cornwall’s steam railway.
You can hop between Padstow and Rock on the ferry. Eating places abound on both sides of the estuary.
A bit further afield you can follow the Fal from Truro to Falmouth or St Mawes and back.
St Ives has terrible parking which has been solved by a great park & ride system on the St Ives Branch Line. You can then reach the Tate and Barbara Hepworth’s house and studio in St Ives.