Fairly confident you can use .50cal there, I'm sure a friend who spends a lot of time there mentioned it a while back.
But yeah, @op this realistically won't work out due to the negative view on guns over here. You wouldn't have the freedom to run this as they do in the US- when I was in the states it was easier to rent a gun and buy ammo than it was to order a mega bucket at the KFC next door. I mean I had to sign a form saying I hadn't felt suicidal in the last 30 days but that was it