i too have been weighing up the ferry options. ports-bilbao is approx £450 whilst the dover calias is cheap as you like and ports-la havre is approx £130.
working it all (almost) out i think the bilbao route would only cost £100 more. this would be easiler if someone could tell me the toll costs for french roads.
from other people the spain ferry is more favourable. just think when you finish after driving for 2-4weeks solid, do you really want to cover the 1500+ miles to make the ferry? or the 600 to bilbao followed by 2 nights rest before the UK? i know its more expensive, but im sure its no more than approx £100
G
these prices were for end sept/oct