We visited Cabo da Roca in 2015. It wasn't a pleasant experience since we arrived amid four big tour buses. People were climbing over the low fence to get better pictures of them at this spot. Hubby nearly got wacked in the head by this woman with a selfie stick!
We loved the lighthouse at Cabo Espichel along with Santuario de Nossa Senhora do Cabo. Such a different experience. The church is lovely and well worth a visit. Yes, we had a rental car and were staying in Sesimbra. It was peaceful and I think only about three other couples that were walking about when we were there. The story of apparition of the Virgin Mary made Cabo Espichel an important pilgrimage site. It was peaceful and much better experience for us.
You can not visit the Lighthouse, only the surrounding area, which is the Roca cape.
Thanks for the responses. We didn't actually want to visit the lighthouse, just take pictures, so that would suit us fine. Unfortunately we won't be renting a car so, while your suggestions sound perfect, we'll have to make the best of what's available. Thanks again.