I support Leicester and England because my dad and friends supported them when I was 6 years old and it just stuck (mostly because of my dad, who brought me up to support them though), not because they are my local teams.
I would imagine 90% of us on here, support Leicester and England for the same reason, if we are honest it has little to do with them being our local teams (though their will be exceptions). Just circumstances from when we were younger with regards to the people around us, that is all.
Though I must say, I am becoming extremely apathetic towards the England national side, it just seems like a case of them making the same mistakes over and over again.
What exactly is the reasoning behind you wanting Arsenal to beat Barcelona because they are English? If you prefer Arsenal as an individual club then fair enough, but why do you want them to win just because they are English. Why does being English make you want them to win?