Ride to Castle Semple, Lochwinnoch - Green ride

Hi Belles, I have a rare Saturday off and a burning desire to visit Castle Semple, off the NCR 7, near Lochwinnoch.
Have not done the ride before, but got directions on my Sat Nav.
So, if you are feeling adventurous, it's about 17 miles to get there. Ride it back with me or take a train back from Lochwinnoch, Johnstone or Paisley.
Quiet roads and cycle paths following NCR 7. Some minor hills. Lunch stop at the visitor's centre.
Pump up your tyres, bring a spare inner tube, water and snacks. Dress for the weather.
The route looks straight forward, but we might get lost a wee bit :-D