Regarding my 550 with the YUN1 camera rig on it I just follow the CAA guidelines, its my own private toy and not for commercial purposes, just for fun. If you're doing fpv you still need to be within line of sight to keep within the rules.
Over 7kg and some restrictions come into force, for instance you can't fly over 400ft and if you're in regulated airspace you need to seek permission.
If you're using one for commercial work you need a license -
http://www.caa.co.uk/default.aspx?catid=1995 so I guess that's something that will need addressing as and when Jimmys beast is built.