
Have a look at the contacts section on
http://thenewfoundlandclub.co.uk for people who will be able to point you in the right direction.
Best of luck with your search but you may have to prepare for a wait as Newfies are still a relatively rare breed and the fact that your looking for brown will narrow your options even more as black is more common and more popular. It took me 18 months to find my pup who just happens to be brown but I had no preference for colour.
Please buy a pup from health tested parents. They should be hip scored (breed average is 29 so anything below this is good), preferably elbows too and a clear eye test within the last year. There are quite a few puppy farmers out there exploiting the high price that Newfies attract. Be wary of anyone selling pups at a knockdown price or charging over the odds.
Oh, by the way, you NEVER own a Newfie. A Newfie most definately owns you :)