With regards to the UK I don't think anyone would be bothered in the slightest. Whilst its your 'Independence Day' no one I know in the UK sees it as the US being negative to the UK in any way and is just another one of 'those holidays' you guys have.
On the other hand I can see why you are wary of the other photo. Its a tough one as countries have worked hard to put 'that' in the past BUT I guess it still happened and can't be brushed under the carpet. That said, it is illegal to sell nazi memorabilia in France and Germany so they thoughts are pretty strong on the matter. The second photo also isn't an account of nazi's but is a staged photo to evoke strong negative (and i guess in some positive) thoughts on the subject so could be viewed as provocative. I would personally air on the side of caution and not use that one.
Just my thoughts.