overview:
http://www.caa.co.uk/default.aspx?CATID=1995
general guidance:
http://www.caa.co.uk/default.aspx?catid=1995&pageid=16011
detailed guidance:
http://www.caa.co.uk/docs/33/CAP722.pdf
text of regulation for microdrones:
http://www.caa.co.uk/default.aspx?catid=1995&pageid=16012
permission for commercial use:
do I need permission?
http://www.caa.co.uk/default.aspx?catid=1995&pagetype=90&pageid=16006
applying for permission:
http://www.caa.co.uk/default.aspx?catid=1995&pagetype=90&pageid=16007
microdrone permission application:
http://www.caa.co.uk/docs/33/SRG1320Issue04Final.pdf