I do not believe that the British will join the army. I think it is more likely that they quit Europe (maybe try to become 51st state of the US).
Believe it or not, but UK is actually one of the best 'european student'. It almost always adopts EU laws, spends a lot of money for the EU institutions, etc.
The only thing they could be blamed for about EU is rejecting the Euro (although a whole lot of shops accepted the european currency last time I went to Scotland) and being basicaly anti-EU