At Paris Orly, missed flight to Porto, cheapest flights there are over £350 now :/
Stuck
Scrap tonight but get your plans in order and tickets sorted. Get out of the airport for a cheaper hotel and have a good time in Paris. (Or sleep in the airport if you're not bothered).
Tomorrow - loads of direct flights to Porto - from Orly and CDG. Ryanair, Transavia, Vueling, TapAir to name a few. All look under £100.
All is not lost here mate. Far from it. It's going to cost you over £100 and a wasted hotel night but by no means terrible - and you could end up having a good time still.