Ahh cute dog..
We have a great dane that we stud off and my girlfriend sometimes uses a site called http://www.preloved.co.uk
to find people looking for a male to vreed with their biatches.
They are a good place to start because you can normally find people who are into breeding certain breeds..
And Prolly the most obvious is http://www.frenchbulldogclubofengland.org/
One thing that is also good to do is just search on google.co.uk for "french bulldog North West" or if your prepared to travel then just leave the north west bit out..
Choosing a doggie that is expensive is a hard thing to do and can also be frustrating if you get a bad bloodline so if you need any advice or tips give me a PM and I will let my missus sort it out!