Lake District Tour Guides & Routes to/from London or Edinburgh

Hi Everybody,
April 20-May 3 in England and Edinburgh. Not nearly enough time to do everything, but we've prioritized and really really want to see the Lake District and spend a few days there. MY questions:
1) Can anyone recommend a good tourguide for private tours? Maybe a full day touring around the Northern LD.
2) We could either be coming from London or Edinburgh--most likely by train. What's the nearest station and how easy is it to arrange trip from that train station to a B&B in Keswick (which is 100% where we'd like to stay).

Thanks in advance,
S