Hi I am driving down to Tortosa at the end of March ,and still planning the route  down.
The last time I drove down i went via the Millau Bridge - la jonquera- Barcelona route  down and return route was via the Cadi Tunnel - Tunnel du Puymorens- Toulouse ,I was thinking about taking the Cadi route again ? but thinking Carretera Lleida-Vielha Tunnel, route might be better less steep hills ? as the trucks use this
Any advise appreciated

Thanks for this,I didn't even know about this tunnel, I've put it in my favourites in via Michelin, and done abit of a search ,I'm basically looking for the best route across fully loaded ,and kindest to my clutch and gearbox ,as its not a new van 😀😀😀😀ive read its quite steep leading up to the Vielha tunnel ?and the same for the Bielsa tunnel  what your thoughts .
Thanks

You could take the Brittany Ferry - Plymouth/Portsmouth to Satander/Bilbao.  Once you have taken all the French tolls, overnight stops, wear & tear, fuel etc. into account it might be the better option.  It is certainly less stressful on the old body!

Thanks to both of you for your replies, I've watched a few videos  on utube, of the approach and exit of the Vielha tunnel /N230 and  Im allot happier now,I've been on that road many years ago,on the Spanish side.but thought it was like the N260 a road that I woundnt want to drive a big old van on,saying that the views on that road are breathtaking.
I've already booked ferry ,Newhaven/Dieppe £200 return,around £150 cheaper than Portsmouth/Le Havre,would have been cheaper, if van was a few millimeters shorter😤 but best to pay now than be caught out once there!
Thanks again
Phil