Very Interesting it would depend on where it takes place, the German's could not displace England through out WW2. If the Brits fight off home soil then Israel has a good chance of winning, but not on home ground.
Britain has a history of not giving the best to its troops, but the soldiers are first rate, and would give as good as they get.
I think pretty much equal in strength.
But I can never see England going to war with Israel anyway.