Well, the EU gravy train is about to hit the buffers as far as Brits are concerned...
You have to be a national of a member state of the organisation.
Here's a list of ticket offices for the gravy train:
List of Co-ordinated Organisations
There are currently six members of the Co-ordinated Organisations. On 31 March 2010, the Western European Union was dissolved by the ten member countries and its competences were transferred to the European Union. EUMETSAT joined Co-ordination on 1 July 2012.
The Council of Europe (CoE)
The European Centre for Medium-Range Weather Forecasts (ECMWF)
The European Space Agency (ESA)
The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT)
The North Atlantic Treaty Organisation (NATO)
The Organisation for Economic Co-operation and Development (OECD)