Culzean Way route thoughts: A roadside path leads from Maidens to Turnberry. Rather than route The Culzean Way along the disused railway track (which had a station at the hotel, but is now a car park), a possibly less expensive and less challenging route may be to upgrade this path between Maidens and Turnberry to a multi use cycle path - that would keep the route closer to the coastline. potentially avoiding main road crossings and give easier access to the lighthouse.
There is a small car park at the entrance to Turnberry Lighthouse. From the car park a well maintained and mostly traffic free path makes a pleasant short walk to the lighthouse.
A cafe called Turnberry Lighthouse Halfway House is open to the public - more information including opening times on Google Maps.