The fastest ferry from England to Spain is on the Plymouth to Santander ferry route in approximately 20 hours and 15 minutes with 2 weekly sailing.

As of my last update, the fastest ferry route from England to Spain typically involves crossing the English Channel and then traveling through France to reach Spain. However, there are no direct ferry services between England and Spain that cross the Bay of Biscay, as the distance is too great for conventional ferry services.

The fastest way to travel by ferry would likely involve a combination of ferry and train or car travel. For example:

1. Take a ferry from England (such as Portsmouth, Plymouth, or Poole) to northern France (such as Caen, Cherbourg, or Le Havre) or to Bilbao in Spain.
2. If you disembark in France, continue your journey by car, train, or another ferry to Spain.

The Brittany Ferries service from Portsmouth to Bilbao is one of the most direct ferry routes, taking approximately 24 hours, but it is not the fastest way to reach Spain from England if speed is your primary concern.

For the fastest travel time, flying is generally the best option, with flights from London to various Spanish cities taking around 2 to 3 hours. If you prefer overland travel, the Eurostar train from London to Paris, followed by a high-speed train (TGV or AVE) to Spain, can also be a quick option, with total travel times varying depending on connections but often taking around 10 to 12 hours to reach cities like Barcelona or Madrid.

Always check the latest schedules and travel options as services can change.