No it wasn't.
With out even clicking your link I would assume you are referring to the channel islands. (Which happen to be in the coastal waters of France)
It was occupied after England withdrew it's few forces from it and had a few bombs dropped on it before the Germans even realized it was undefended. It was then occupied and can in no way be considered an invasion of England. And not to diminish the difficulties and privations suffered by the inhabitants it really had very little strategic military and economic value and England did not even bother defending it and they were not liberated until the day after Germany surrendered.
But why beat up MichelSableheart? His rhetorical question is very historically accurate.
But anyway. I appreciate that mainland England can not be invaded in the game.