am searching the net for info on rental signs like NO IRISH NO DOGS addressed at Polish migrants
Why?
First, it's illegal. It violates the European Convention on Human Rights, and probably many UK laws.
Times have changed.
In the time period when you could see "No Irish" signs, it was not illegal.
I think even in Myanmar, today, you can't put up a sign saying "No Poles".
So, you won't find what you are searching for. Also, again, why are you searching for this? Is this forum not enough, where you can find probably 1,000 pages of Brits complaining about Poles in their country?
Who needs signs when there is a whole ocean of hatred on the internet?