Hi. I've also posted this message onto main forum and again apologise if it's old news, but I've only just heard of it.
P&O have posted a press release on their website stating that all ferries to and from Portsmouth/Bilbao have been cancelled from 27 Septembert 2010 due to financial difficulties. I reckon there could now be a rush to book with Brittany Ferries which could well force up prices due to high demand, so may be worth booking early if you're planning a winter escape to or from Espana!
Happy Travelling