Reckon your best bet in West Yorkshire is to give Rob Collins a shout, he is in Hebdon Bridge. Although he doesn't specifically list supplies on his website he is usually happy to oblige. Top bloke he is.
As for what timber to use, ask ten people on the forum and you will get 10 different answers! Personally I don't think you can go wrong with mahogany. Time honored, pretty cheap and as easy as anything else to work with. Have a chat with Rob, he can advise.
Just realised that you're at the opposite end of Wales from where I'll be stopping in a couple of weeks. Shame, but it's probably saved me from knocking on your door and throwing money at you.