You say you are collecting your new puppy next week and is only 5 weeks old now. You seem ok with this i would not want to pick a puppy up as early
as 6 weeks as it will only just have got used to weaning and started socialising.

I would never let my puppies go until at least 8 weeks old and even longer if needed. I find it irresponsible of the breeder to let it go so early!! Will it be vaccinated or health checked?? I would be very dubious about having a pup from someone who let them go so young. Are they reputable breeders? Will you get insurance? or a life time of support?