>> whereas 1:50,000 are better for motoring towards your chosen site.
Well, they're ok for the final approach, but I wouldn't want to navigate from Birmingham to Lewis using 1:50,000 scale maps :-)
Even better for detail if you can get it - 1:10,000 - often used in electronic format by councils etc. It gives much more info about springs and watercourses and such.
how else do you know where all the mileposts and telephone boxes are?
(not too mention pubs)