Hi and thanks for your great question!
You are absolutely correct – socialisation for puppies is vital from 8-16 weeks of age. For this reason isolation, with no other canine contact, can be very detrimental for future interactions with dogs in adult life. Puppy school is usually very safe, especially when run from a veterinary clinic or other reputable organisation where all puppies are required to show documentation of up to date vaccinations. My only hesitation with puppy classes is that overly timid or dominant puppies can (if not properly supervised) have these traits reinforced through unsupervised puppy play time.
I would certainly recommend taking your little pooch to the classes, just be mindful of overly dominant behaviour towards smaller puppies to ensure that your labradoodle doesn’t develop any little dog aversions!