Hi Angela & Tony,
Just got home today after a long drive back, you don't mention where you're starting from but I'm sure you'll be able to adjust accordingly.
We drove 1470 miles each way from West Mids & it took 27 hours going & 26 hours back. These included several stops for food/toilet breaks also time checking in on Eurotunnel.
The roads were mostly great except going down we encountered heavy snow falls through the Pyrennes between Clermont-Ferrand & Prepignan, though the roads were kept quite clear we did have to take care because of the conditions (only probs on return was a spell of fog).
Fuel costs varied with France being the highest (average 1.07 euro motorway/ 0.98 euro normal) per litre of diesel, Spain averaged (0.85 euro motorway/ 0.80 euro normal). I'm sure you're aware of U.K. prices.
We chose the 'fastest' option on the satnav (which also mirrored the Michelin downloadable route), but included the dreaded TOLL ROADS!!!, prices for our van were as follows: -
France, 30.40euro, 52.90euro, 8.50euro & 16.40euro, total 108.20euro
Spain, 11.65euro, 3.80euro, 3.40euro, 5.25euro, 21.00euro, 3.50euro & 3.50euro, total 52.10euro.
I've tried to put these in sequence & are obviously reversed on return leg.
I hope some of this helps & I hope you have a safe journey. I will add though, as we have just found out, with the exchange rate as it is at the moment, it was very worthwhile doing & get as much in U.K. as possible(even your food shopping), because we may not be as 'ripped-off' as we think we are.
Dave