Conchas place is great and it is perfect for a solo traveler! I highly recommend getting a bike on the main road so you can see all of the city without needing a bus pass.
Her place is very basic and I used it for the basics. You only have access to the bathroom, your bedroom and kitchen. Concha is a great host and picked me up and dropped me off so I wouldn’t have to with all bags. She is very particular about her house and her rules but remember you are a paying customer!
San Sebastián is an awesome place with great food.. enjoy it!