I have one booked in a few weeks time, they know I've not done one before but I said I'd looked on the Club website to see what they were groomed like and could do her. Looks like they are fairly short all over with a roundish head and moustache/beard sort of thing. Does anyone happen to know if you can clip the body on a 3/4 blade or something, or if you have to use straight scissors or thinning scissors? I want to do a good job!

How about joining their forum and asking?

I searched for grooming on the club website and didn't find anything useful, I didn't notice a forum but will look again, thanks.

I'm not 100% sure but from memory of talking to show owners of Lagottos, they are clipped all over with a longer blade than the Spanish & their heads are scissored.  The Spanish are clipped the same length all over, but the Lagottos have "bigger heads".  this was 5 years ago so things may have changed.

Not an english site but may give you an idea:

http://www.greydove.com.au/grooming.cfm

From a quick google search it looks like even people 'in' the breed have different ideas and methods but the most common one I found was clip then keep trimming for the next 3 months and then the coat will be in the style/length for showing.

Never done a Spanish either! But thanks for all the links and suggestions people! :-)