i'm not knocking your aims , but a few points come to mind.
a) unless you are a representative of a major group (such a greenpeace), or one of mr browns constituents - I would rate your chances of arranging a face to face meeting with the PM as approximately nil
b) this being the case wouldnt you be better off setting up a petition on the downing streeet website , or indeed promoting one of the anti whaling petitions already running, or one of the ones based on the main organisation websirtes , greenpeace , IFAW etc ( a link to the iFAW website campaign against whaling can be found here
http://www.ifaw.org/ifaw/general/def...17846&aid=9466 )
c) The UK doesnt do whaling anyway - so wouldnt it make more sense to target the nations that do (iceland, russia, japan principally)
and
d) if you are set on doing your own , there is some evidence to suggest that the govt logs petitions from individuals as one piece of correspondence regardless of how many names there are on it - therefore it is better to provide a form letter and get people to email it to their MP or MEP individually.