Sarah
Run, don't walk, away from that breeder. She is in violation of the UK Breeding and Sale of Dogs (Welfare) Act, by selling a puppy under 8 weeks of age. Look for a responsible breeder in Wales. (BTW I am half Welsh - Monmouthshire, have many happy memories of visiting my grandparents) I was raised in England.
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Breeding and Sale of Dogs (Welfare) Act 1999
Breeders who breed four or more litters per year must be licensed by their local authority. Breeders with fewer litters must also be licensed if they are carrying out a business of breeding dogs for sale.
Licensed breeders must:
a) Not mate a bitch less than 12 months old.
b) Not whelp more than six litters from a bitch.
c) Not whelp two litters within a 12 month period from the same bitch.
d) Keep accurate records.
e) Not sell a puppy until it is at least eight weeks of age, other than to a keeper of a licensed pet shop
or Scottish rearing establishment.