Some good advice here. I wanted to put my 2 centavos into the ring and support the notion that you should research the breed. Purebred dogs have the benefit of having some common characteristics. I would determine what kind of lifestyle I live and then try to find a breed that best matches it.

If you work and no one is home during the day then a puppy may not be for you. I'm not sure if in the UK there are breed rescues but in the US there are specific breed rescues through out the country. That avenue has the benefit of going through people who know the breed and have done the leg work to match you up with the best dog/bitch. They also take care of the medical work and have temperament tested the dog.

Another avenue would be to find a RESPONSIBLE breeder. Many breeders have adults that they are trying to home. This avenue is more expensive initially but may be cheaper in the long run due to the careful breeding resulting in cheaper medical expenses.

Good luck with whatever you do and keep us updated.