There's a White MK6 Golf GTi that's an unmarked police car used here in Norwich. I've driven past it a few times & had to do a double take as I thought I was imagining it at first.
The car you've linked to does look tidy, but it's probably not had an easy life at all, so possibly best to wait for another one to come along as others have suggested.
As for distance, I traveled 100+ miles to get mine & had to drive it out of London (something I've never done before), so try not to be put off by distance. If it's the right one, distance shouldn't matter, and if you speak to most dealers, they are sometimes happy to cover costs, one was even prepared to cover my travel, hotel & show me around the city. I was very impressed with the service I received from the London dealers & I wouldn't hesitate to purchase from them again. Next time I'm hoping I'll be shopping for an R.

Best of luck in your search bud!