This is the raw HTML from the British National Formulary site, currently at version 65 (March 2013). Provided for research purposes only, or something like that. My tiny contribution to the NHS Hack Day.
If you're not comfortable with using git, you can download the files directly.
The site starts at www.medicinescomplete.com/mc/bnf/current/index.htm.
wget --load-cookies cookies.txt --mirror --no-parent --convert-links --page-requisites http://www.medicinescomplete.com/mc/bnf/current/
cookies.txt is not provided, as it's unique for each user account. To generate your own cookies.txt, log in to the BNF site, and use the Export Cookies extension for Firefox to dump all your cookies to the missing cookies.txt file.