I do not live anywhere near Porto so don't actually know specifically about services. However, have a look at this page (in Portuguese) which is about the Porto Cathedral.
http://www.diocese-porto.pt/catedral/igreja.htm
This is the link for the Diocese of Porto web site:
http://www.diocese-porto.pt/
If you click on the Links item at top left of the page you will come to a list of parishes with websites in the Diocese including Porto.
