P&O are still doing the Biscay route to Bilbao. They don't do any routes to Northern France from Portsmouth.
The Portsmouth to Le Havre route is being run by an Italian firm
http://www.ldline.co.uk/ppc.html
To do a return trip involving a ferry to Spain, road travel through France and a Channel crossing back to the UK with P&O means using Calais to Dover.
For me, nicer ferries, shorter travel time on the ferry to Spain and the shorter distance to get back home make the Brittany Ferries option more attractive. The P&O price would have to be much cheaper for me to consider using their inferior service.