I've been driving to Spain for the last 12 or 13 years, I've only once had a problem and that was with the ZS
, most of the other cars have been old wreaks but they've all been fine.
The last 2 times we went we used the Portsmouth/Bilbao ferry on the way out as it makes for a nice relaxed arrival, as my mother-in-law lives 15 minutes from the ferry terminal, we still normally drive back via Calais, only a 780 mile drive.