Technically, although you have a seat in first (because there is no busines cabin), you are still travelling on the business class fare throughout. So you are subject to the restrictions of that fare and will also earn points etc throughout the journey based on the business fare class. Which means that if you buy a (P) fare, you get no lounge access throughout (unless you have some airline FF status and can use one of the status lounges). QR do offer Al Safwa access to business fare holders travelling in the first cabin on intra-gulf route, but only as long as their business fare does not exclude lounge lounge access - ie (P).