Thanks. 
It went very well. The trainer was as good as her word and had set us up in a corner slightly away from the other pups, she also got someone to wait with us in the entrance hall until everyone else was settled, then let me bring him in at his own pace and settle him down.
When we arrived outside he was totally freaked out at seeing so many puppies, tried to bolt, then flatly refused to move. In the end I picked him and the poor mite was shaking like a leaf. Would it be wrong to admit that I was relieved to see a few other puppies having to be reluctantly dragged in. 
The only pup we were near was an absolutely gorgeous, tiny Border Terrier puppy. She's only 8 weeks, so hasn't had her jabs yet and was kept away from the other dogs for that reason.
Pip spent the first half of the lesson either behind or under my chair, being clicked and treated for every foray forwards and for calmly watching the other dogs. It took about 15 minutes for him to stop shaking and another 20 odd to start venturing out, but by the end he'd decided the most rewarding place to be was in front of my chair and he was happy to sit and watch all the other puppies being trained.
The Cockerpoo next to us tried all his cutest tricks to get Pip to play with him and Pip just sat and watched him with big eyes, but he allowed him to come quite close and didn't back away or panic - so it's all looking very hopeful.
The class is quite small - only 8 puppies including Pip. 2 black and white Cockers, 2 Cockerpoos, a Springer and a deaf Jack Russell and another pup that was on the other side of the class and I think was possibly also a Cockerpoo, plus the trainer's adult Toller and the teeny Border Terrier girl.
Mum took us for lunch at the dog-friendly cafe afterwards and Pip was able to watch another dog in there as well. He was so exhausted when we got home though. He ate his dinner in his kongs while I fetched the dcs and has been snoring away every since. 
Unfortunately I now have a migraine (shouldn't be on here, but didn't want to leave you all hanging) and when I picked dd up, after her first day back at school she looked dreadful. Got her home - temp of just under 40 degrees. It's come down a degree with calpol, but she's having chills and is very sleepy. She's still insisting she's well enough to go tomorrow though.
Praying she's well enough to go in on Friday, as she's so desperate to wear her book day costume. 
Off to lie down next to dd myself now. Dh is coming home early - but is going out to a gig tonight, so I'm hoping dd doesn't get any worse.