Get in touch with the Weimaraner Club of Great Britain and/or the Weimaraner Association
http://www.weimaranerclubofgreatbritain.org.ukhttp://www.weimaraner-association.org.uk/who will put you in touch with reputable breeders who, if members of these organizations, must abide my a code of ethics/conduct where they agree not to mate a bitch under 2 or produce a litter over 7 nor have more than 3 litters per bitch in her lifetime. Members agree only to breed from stock that meet the breed standard and that are temperamentally and physically sound. They also agree to help with rehoming should the need arise. You should buy only from breeders who hip score both sire and dam (the breed average is 13).
HTH