Just for your info Steve, I emailed Zotal about the suitability and here's what they came back with:-
Dear Sir,
"As you well said, Jeyes fluid is not sold in Spain. Our product Zotal is a formula very close in composition, but substituting the “natural phenols” present in Jeyes by “Synthetic Phenols”. The base is quite similar, and actually we know that our product is used to disinfect different items by quite a few farmers. Unfortunately, our product is not specifically registered to sterilise pottery and soil, being only approved to be used for the disinfection of surfaces and other items. Thus I cannot provide you with any accurate dosage to be used for the disinfection of soil. The product being similar, I guess the same dosage could be used, but I must inform you that we have no previous experience in disinfecting planting soil. Perhaps a preliminary test with several olives could be recommended?
Best regards,
Enrique Ruiz
R & D Manager
Laboratorios Zotal"
Very helpful I thought.  I haven't got time to do test planting so it'll probably have to be all or nothing.  Should be OK with fertiliser after planting to give the roots a good start.