People who live in the South-East might be interested in this event on the French-Belgian border next weekend (2 July). It's just a few minutes drive from Dunkirk. There should be plenty of time to meet people, find some caches in two countries, and drop in at the wine discounters on the way back.
Plus, with the way the Belgian "language border" works, the Belgians will be Dutch-speaking and the French people won't. So a lot of people will be speaking English anyway.