Looking at the figures for each nations military it looks like there is a high chance of it developing into a slugging match between the nations with the biggest populations. Looking at a map of Europe if Britain and Ireland work together with the Nordic countries they can control the North Sea and the Channel, and chances are overwhelm anything Spain and Portugal can throw up to try and keep control of the ocean. France might not be able to last or focus for long if it isn't careful because it is quite easy for Spain, Germany or the Uk to attack from multiple directions, so playing over nations against each over to prevent power blocs from forming and forming alliances if its own are going to be important if it wants to survive.
I'd hate to be Switzerland though. ouch doesn't quite cover it.
