http://www.poferries.com/tourist/
P&O Ferries boasts the largest fleet of ships offering a wide range of services and facilities, the most comprehensive route network and the most frequent passenger and freight services to the Continent.
http://www.brittany-ferries.co.uk/
Brittany Ferries operates one of the most modern fleets on the Channel, with 8 ships and over 2,500 employees. It accounts for over 50% of the traffic on the Western Channel.
http://www.ferrysavers.com/
Ferrysavers.com provides an online booking facility for all major European ferry operators in real time, including a simple price comparison facility.