@GrahamPaul I’ve looked at a few like Enduro Malaga and Basque MTB (as seen on Mctrail rider) and would like some other recommendations if you have them please. Great idea about the ferry.
Okay, here are a few suggestions for you.
Obviously there are the two companies you've already mentioned from McTrail:
but there is also
TrackMTB from his adventures nearer Madrid.
But if you are heading across the water into Northern Spain then you will probably be thinking of the Mecca of mountain biking,
Zona Zero, about 4 hours drive from Bilboa. This is stacked out with touring companies, uplift services and just about everything to make your life easy.
The following are links to some of the Zona Zero guide companies, starting with those in English, are:
Depending on how independent you wish to be, it's dead easy to plan your own itinerary. Many regions of Spain have set up "cooperatives" which recognise that MTB tourists bring in lots of custom to areas which would otherwise be dead. You can basically get off the ferry and start your ride in the Basque Country, using
this website. Warning, which is on the website, fitness required! Google translate will handle the web pages for you
An area where I was earlier this year is about 5 hours drive from Bilboa. Really friendly, great prices - and a short hop over the border from the Portuguese National Parks if you feel like a change of language and culture.
Aldeadávila de la Ribera has a well laid out and waymarked MTB system - some of it decidedly technical.
A bit further afield is
Enduroland MTB, which is a bit North and inland from Valencia.
Lastly, there are the mostly Brit run places down here in Andalucia. I have listed below the ones around Malaga province. Going East into the Tabernas desert of Murcia there are even more. The advantage is all year round biking - although possibly not today!
As I was going through the list I was rather thinking about the specifics of EMTB travel. All of the guiding companies offer uplift services. Most of the runs are gravity with not a lot of pedalling needed. That rather defeats the concept of an EMTB, no? Personally, I've never used a guiding service, prefering to choose my own routes after doing my own research. Even for Aínsa (Zona Zero) all of the waymarked routes are published, with GPS tracks (but they are well marked anyway), so why would you really
need a guide? Okay, if you want to go balls out on a downhill you've never seen before, I can understand the idea of taking a lead from someone who knows where they are going. But, with the EMTB, that climb to the top for a second run surely isn't going to be a problem.
BTW, the Zona Zero, Basque Country and Aldeadávila websites all list accomodation, uplift taxis, repair shops, hire places etc. So doing it oneself really is no great effort. (We usually camp - in campsites. Fly camping in Spain risks massive fines).