Paula is amazing! She knew I was traveling alone and taking a train into Estoril and went out of her way to drive around town in hopes of finding me and kindly giving me a ride to the apartment - SO sweet! The apartment is charming and although lived in, tidy and clean and the best part, a quick walk to the beach! You can easily (30min) and safely walk the boardwalk to Cascais for dinner (amazing sunsets) and take a 5€ cab/Uber back if you don't want to stroll at night.
The train does rumble past but I didn't find it too bad and slept soundly. If you're a light sleeper, bring ear plugs!