Figures for military spending by various countries are provided by the Centre for Defense Information.
An Irish organisation campaigning against Irish involvement in the arms trade is AfRI (Action from Ireland): here is their web page on the subject.
There are also local activities aginst the arms trade in Derry (Foyle Ethical Investment Campaign) and Belfast (Irish Network for Nonviolent Action Training and Education).
A British organisation campaigning on this issue is the Campaign against Arms Trade.
There is also a European Network against the Arms Trade and the International Peace Bureau-Italia studies regulations in the EU member states.