Is street photography ok/accepted in UK, Portugal, Belgium and Germany?

I am not aware of any country in Western Europe with a blanket ban on street photography.

Some countries have complex privacy law (including case law) that makes publishing photo of persons without prior written authorization potentially sensitive but that's a completely different issue. “Copyright” protection is also very extensive and can extend to buildings or lightning (most famously the Tour Eiffel light show) in ways that would not hold in the US.

Finally, what got Google Street View in Germany are data protection laws. Each EU country has a data protection authority in charge of overseeing/controlling all files that contain personal information, which, in Germany, was deemed to include pictures of your residence. The issue here is automated processing/systematic publication, not taking pictures per se.

So taking pictures for your own use or even publishing them in the US is almost certainly not an issue but any sort of local use (especially commercial) is fraught with difficulties, especially if there are people on the picture.

Quite apart from the details of the law, I have heard about some people getting angry at being photographed so in a way street photography is not fully accepted in Europe.

In Germany you can take photos for personal reasons as much as you like. If you tak pictures of persons you should ask however.

Legal restrictions exist for publishing due to personality rights and copyright. The Kunsturhebergesetzt (Copy right law for works of art) prevents publishing photos where persons are the central part of the picture (i.e. if you take a picture of a monument and a person runs by this is legally no problem) The Urhebergesetz (copyright law) otherwise regulates that reproduction of copyrighted material requires permission of the copyright holder. Buildings are copyrighted by the Architect. There however is the so called Panoramafreiheit (freedom of panorama) which allows pictures of buildings from publicly available spaces.

The Google Street View situation is not based on legal restrictions, however. When Google started taking their pictures there was a big campaign by media stating that Google would take too many pictures and people feared those pictures would look through windows and would show too much detail. To avoid further conflict Google then volunteered to offer a way for house owners etc. to blur out their buildings.

In general people in Germany are concerned about their privacy which might make this even more complicated than the law.

A few months ago, this issue was up for debate in the European Parliament. Whether the Freedom of Panorama, FoP, was going to be restricted within the EU was going to be up for a vote on July 9. The bill in question would require "commercial use of such reproductions [to] require authorization from the right holder".

However, due, in part to a write-in campaign, FoP was saved, for those countries that had it to begin with. This includes Germany, but not France, Italy, Belgium and Greece.

Germany does have rather strict privacy laws. Here's a somewhat old blog post with some additional info, specifically on photography in public places.

As for Poland, I have never heard of that. I have read about the privacy law(at least when it comes for making photos of people), and rule of thumb is: you can't disclose any information that would allow the identification of some individual(name, personal ID, card number, but this also includes photos/videos), but you can keep them for your personal use.

I also guess(although I can't remember nor do I have time to check that now) that there's some special case allowing you to show other people when it comes to some public events; television does that all the time.

There is a nice summary available on Wikimedia describing how the consent rules vary by country: https://commons.wikimedia.org/wiki/Commons:Country_specific_consent_requirements

Similar page allows to check the local freedom of panorama rules: https://commons.wikimedia.org/wiki/Commons:Freedom_of_panorama

Each street photographer has their own style and work ethics but from my experience, whatever the law permits, one should never sneak but rather be very open with the intention of taking the picture and smile a lot (nothing beats that one). This helps to avoid many unpleasant situations and makes the trip more enjoyable.