It seems that here in the UK, we are pretty open with regards to the fact that we can, when standing in a public place, take a photograph of anyone or anything we want, and use it for any purpose whatsoever without the need to complete any forms.

No we can't

http://en.wikipedia.org/wiki/Panoramafreiheit

http://de.wikipedia.org/wiki/Panoramafreiheit#Gro.C3.9Fbritannien

The  most photographer-friendly country seems to be Austria.

The freedom of panorama is defined in section 62 of the United Kingdom Copyright, Designs and Patents Act 1988, but it doesn't mean you can shoot and sell anything. No serious agency would accept photos of Piccadilly Circus for commercial RF because of the logos. I also read that places protected by the National Trust are very problematic and can't be photographed freely.

Apart from copyright issues, in the UK a photographer is sometimes treated as a criminal.
When I was in London in 2008, I was grabbed a couple of times by guards in Canary Wharf, some wanted to see if the camera really captured photos, others told me to go away. I also had to show the contents of my backpack to policemen. When I was photographing the Big Ben I had to show my passport to the Bobbies...
Rather unpleasant.

It seems that here in the UK, we are pretty open with regards to the fact that we can, when standing in a public place, take a photograph of anyone or anything we want, and use it for any purpose whatsoever without the need to complete

What makes you imagine that?
Yes, we can take photos when we're in a public place. Yes, we can sell them for editorial use.
Sell them for commercial use or use them in any way which distorts truth or subjects a person to riducule and you could find yourself in deep sh*t. (Simple example: you shoot a group of people at a table inside a pub, and it's published with a caption implying that they're all enjoying alchoholic beverages. One of them is a well-known teetotaler and was drinking a soft drink. They're perfectly at liberty to sue, though who would bear the brunt - you or the publication - could depend on several factors.

...implying that they're all enjoying alchoholic beverages. One of them is a well-known teetotaler and was drinking a soft drink. They're perfectly at liberty to sue...

I'd sue them if they portrayed me as a teetotaler