It's very, very different in the UK. Most small dogs leave their mum/litter mates at 8 weeks....right or wrong - that's how it's always been, large or small breeds.
We
happened to get Harry at 12 weeks - but's that's just how it was....happened
EVERY other dog I've had (Boxers, Labs, Westies, miniature Schnauzers etc etc) have ALL been 8 weeks old. One of Harry's littermates (the little girl) went to her new home at 8 weeks. She is gorgeous and well-adjusted and trouble-free.
If I were you, I'd go along anyway, and explain the situation, and your doubts and worries. That you've read so much and learnt so much - bite inhibition, fear of blood sugar dropping in a Littlie etc....assess the whole situation, and the set-up, and the responses you get - and THEN make your decision.
Hard, isn't it? But I wish you luck - and hope tomorrow goes really well for you
Sally + Harry x